Harlequinmania

Click through to see the images. As reported by LaughingSquid, Oceanwings are a wetsuit inspired by skydiving wingsuits and reportedly gives the wearer the feeling of flying underwater. The suit is designed by Guillaume Binard, who partnered with AquaLung to create the suit for the Paris Dive Show in last month. World renound freediver Pierre Frolla put the suit to the test in the video below. There is no word at this time if the suit will be manufactured. What do you think - would you try one if you had the opportunity? View the full article

Click through to see the images. Media reactors are very simple in principle and purpose: Force aquarium water through media (e.g. activated carbon, GFO, bio-pellets) within a contained area. As such, most media reactors throughout the decades are similar to one another ... and quite frankly most designs are rather uninspired. Then there is the new, patent-pending Innovative Marine MiniMax media reactors. We're not a blog known for gushing superlatives, but these reactors are brilliantly designed. What really distinguishes the MiniMax is their ingenious double-sleeve cartridge design, which enables both a unique, responsive flow control as well as an ingenious method to replace media. IM's video (below) clearly demonstrates how the MiniMax reactors work: As you can see in the video promo, replacing the media in the IM MiniMax is fast and mess-free. And this is a big deal in our opinions. Too often aquarists do not replace their media as often as they should (particularly activated carbon) due to the mess and hassle of changing medias. With conventional media reactors, you would have remove the entire reactor to change the media. In contrast, the self-draining cartridge-style system of the MiniMax makes changing media a cinch. The new MiniMax line will premiere with two models, both in-sump/in-tank reactors designed for smaller aquariums; See below for more information. We would love to see this novel design adapted for larger reactors. It's not often a media reactor gets us excited, but the Innovative Marine MiniMax proves that with some out-of-the-box thinking, you can teach old dogs new tricks. Innovative Marine supplied Advanced Aquarist with the following information: MiniMax – All-In-One Media Reactor If you desire the highest water quality but are frustrated with media reactors on the market….Meet the all new MiniMax. The MiniMax All-In-One Media Reactor is a novel approach to optimize chemical and biological filtration for nano & mini marine aquariums. Its’ innovative Patent Pending design minimizes the need for flexible tubes, pvc pipes, ball valves, thumb screws, and unnecessary clutter that are usually associated with typical media reactors. Its’ ingenious design maximizes performance and offers out of the box responsive flow control, easy maintenance, low power consumption, and the smallest form factor ever built. The versatile MiniMax is designed to be discreetly hidden behind All-In-One Aquariums or placed directly in sumps. The MiniMax is the All-In-One reactor for All-In-One Aquariums Responsive Flow Control – Unique dual chamber design, allows for quick and responsive flow control within seconds with a simple turn of knob without the need for ball valves and inlet/outlet pipes Efficiency – Utilizes upward flow pattern that requires less flow and lower energy consumption (Desktop Model – requires a mere 2.5 watts) Eliminate Messy Maintenance– Internal chamber acts as a removable cartridge that simply slides out of outer chamber and automatically drains water out without the need for tools and time consuming thumb screws to unfasten. Nano Size – We produced the smallest Nano Reactor (2†x 2.3†x 11.4â€) with the integrated features right out the box Features: All-In-One Design – for use with Bio Pellets, GFO, & Carbon Made from quality cell cast acrylic – Bracket Included Smallest Form Factor Responsive Flow Control Low Power Consumption Double O-Ring Seal for Lid Offered in Desktop (150ml Max Volume Capacity) & Midsize (350ml Max Volume Capacity) Pump Included Just add your favorite Media Pricing: Item Number 7301 – Desktop MiniMax All-In-One Media Reactor MSRP $ 99 Item Number 7302 – Mid-Size MiniMax All-In-One Media Reactor MSRP $ 129 View the full article

Click through to see the images. I just couldn't post this on Valentine's Day (but maybe I should have?). Scientists studying the nudibranch Chromodoris reticulata (pictured above) discovered something startling when analyzing their mating behavior. The nudibranch has the ability to slough off its penis after copulation and regenerate it afterward! The results of this study are published this week in the journal Biology Letters (pdf access available). Chromodoris reticulata is a simultaneous hermaphrodites, meaning it possesses both male and female genitalia. Self-fertilization does not normally occur so it must mate with other individuals in order to reproduce. What the scientists did was collect specimens from a dive trip off the coast of Okinawa, Japan, and observed their reproductive behavior in aquarium settings: Mating and morphology of the penis in Chromodoris reticulata. (a, Two individuals reciprocally insert their penis into the partner’s vagina. (c,d) Autotomized penes after copulation; the tip of the penis is swollen. A mass of sperm (sp) is attached to the thorny penis in (d). They observed that 15-30 minutes after copulation, the nudibranch shed its penis and then regrew it in roughly 24 hours. The regrowth came from a spiral structure that extended outward after copulation, kind of like unspooling thread. This unspooled tissue regenerated into a fully functional penis and allowed the nudibranch to copulate for as many as three times in three days before it became exhausted. (via Science: ScienceShot) View the full article

Click through to see the images. The hotel says fortunately no animals were harmed. But imagine if the tank had broken due to this man's intoxicated escapade ... " height="390" style="width: 640px;" type="application/x-shockwave-flash" width="640"> "> "> View the full article

Using underwater video cameras to record fish feeding on South Pacific coral reefs, scientists have found that herbivorous fish can be picky eaters - a trait that could spell trouble for endangered reef systems. (2013-02-14) View the full article

Click through to see the images. BERKELEY CA (February 12, 2013) – The Larger Pacific Striped Octopus displays striking color and shape changes, shifting in an instant from a nondescript dark reddish black “leaf”, to an awesome clash of white and black stripes over constellations of white spots. Two San Francisco Bay Area scientists, Dr. Roy Caldwell of UC Berkeley and Richard Ross of the Steinhart Aquarium in the California Academy of Sciences (working from his home lab), are studying this long ignored and little studied Central American octopus. Caldwell, who studies such showy creatures as blue-ringed octopuses, says “The Larger Pacific Striped Octopus is the most beautiful octopus I have ever seen”. Besides coloration, what makes the Larger Pacific Striped Octopus so different from other octopuses is the way it seems to ignore what has become the standard story of octopus social structures, mating and motherhood. Instead of living a solitary life, and coming together briefly for mating like almost all other octopuses, the Larger Pacific Striped Octopus can cohabitate in pairs, sometimes sharing the same den. Groups are reported to live in associations of 40 or more animals. Instead of mating from a safe distance like most other octopuses, or males mounting females as occurs in a few others, the Larger Pacific Striped Octopus are the only octopuses known to mate “beak to beak” with their ventral, suckered sides touching—a position that may be viewed as dangerous considering the cannibalistic nature of cephalopods. The Larger Pacific Octopus mating 'Beak to Beak'. Most female octopuses mate and brood a single clutch of eggs through hatching, only to die as their offspring swim into the great unknown. The Larger Pacific Striped Octopus breaks this tragic tradition. The female Larger Pacific Striped Octopus is iteroparous meaning that she lays and broods many clutches of eggs over her lifetime. One of the only other octopuses known to share this trait is the Lesser Pacific Striped Octopus (Octopus chierchiae), a tiny close relative to the Larger Pacific Striped Octopus. Until Caldwell and Ross began studying the Larger Pacific Striped Octopus, the creature was virtually ignored. In 1991, Arcadio Rodaniche published a short abstract “Notes on the Behavior of the Larger Pacific Striped Octopus, An Undescribed Species of the Genus Octopus”, providing a tantalizing glimpse of this intriguing animal based on observations he made at the Smithsonian Tropical Research Institute in Panama in the late 70’s. Unfortunately, detailed information contained in a full manuscript documenting the Larger Pacific Striped Octopus’s unique social and reproductive behavior was never published. According to Caldwell, Rodaniche’s descriptions of the behavior of this species were so outside the norm of what biologists at the time thought octopuses did, they were dismissed by other cephalopod biologists. Unable to pass peer review, the manuscript was never published and the animal was forgotten. Living LPSOs weren’t seen again until they were rediscovered last year. According to Ross “We are thrilled to confirm many of Rodaniche’s observations”. Caldwell, Ross and colleagues are currently working on a species description, a behavioral paper on the LPSO and are hoping to mount an expedition to document the behavior of this octopus in its natural habitat. Watch the LPSO change color: Roy Caldwell, rlcaldwell@berkeley.edu (510) 642-1391 Richard Ross, rross@calacademy.org (510) 928 9247 View the full article

Click through to see the images. You can read more information about this blue tomato clown over at 3reef.com. iBluewater.com provides Advanced Aquarist with three new photos. The photo below shows the small blue male with his large, typically-pigmented female mate. View the full article

Click through to see the images. It was 2005 when I last wrote an article presenting results of a comparison between Photosynthetically Active Radiation (PAR) meters, and the lamps used during testing were metal halides of various kelvin ratings (see Riddle, 2007). In those days, the use of light-emitting diodes (LEDs) for aquaria was something discussed by only a few. Nowadays, use of metal halide lamps is much less popular and usually seen over larger aquaria or those of die-hard fans, yet, to my knowledge, there have been no updates on the utility of different brand PAR meters and their responses when judging output of LEDs. This article will compare the responses of three quantum meters when measuring LED light output. Specifically, these are meters manufactured by Apogee Instrumentsâ„¢ (model QMSW-SS; Logan, Utah), Li-Cor Biosciencesâ„¢ (LI-1400 datalogger and LI-189 sensor; Lincoln, Nebraska) and Spectrum Technologiesâ„¢ (FieldScout; Plainfield, Illinois). Product Details Li-Cor LI-1400 Quantum Meter and LI-189 Sensor Li-Cor Biosciences (Lincoln, Nebraska, USA) is noted for quality instruments, and their meter/sensor combinations have gained wide acceptance within the scientific community. Quality comes at a price (the referenced combination currently costs more than $3,000). The sensor construction is an intricate one - see Figure 1. In addition, the sensor is relatively large and the cord exits the bottom. These facts restrict its use to larger aquaria. Figure 1. Typical construction of an expensive PAR sensor, such as Li-Cor's. From Kirk, 2000. Apogee Quantum Meter Apogee Instruments (Logan, Utah, USA) manufactures entry-level PAR meters and sensors, and many hobbyists have found favor with them due to their affordability. The sensor is relatively small and its cord exits the side making it ideal for use in tight quarters (such as aquaria). FieldScout Quantum Meter Spectrum Technologies (Plainfield, Illinois, USA) manufacturers a number of products aimed at the agricultural/horticultural markets. Although the meter tested here is the FieldScout Light Meter, the sensors are interchangeable with other Spectrum products (such as their wonderful WatchDog datalogger). The sensor tested here was custom-built for my lab for use when testing artificial light sources. Spectrum does not recommend their quantum sensor for use with LEDs but I wondered just how much of an error there actually is, hence I have included it in this review. In all fairness, we're comparing an expensive instrument (the Li-Cor setup costing over $3,000) to relatively inexpensive ($300-$400 or so) units. A calibrated light source would be needed to accurately judge the responses of all three meters. This luxury was not available for this review, hence the Li-Cor meter - based on the advertised responses of all three meters - will be considered 'correct'. There are several things that can affect a quantum meter's reading, these include: Spectral sensitivity of the sensor Spectral quality of the light Sensor Cosine Correction Sensor Construction (2 pi or 4 pi) Testing medium (air, water, etc.) Condition of the sensor (physical damage, age - 'fogging' of optical components, cleanliness) Sensor/meter calibration Temperature Light source used for calibration by the manufacturer These terms will be used throughout this article: Glossary Actinity Error: A perfect PAR sensor would be equally responsive to all wavelengths of light between 400nm and 700nm. In practice, this is not possible and response difference between a real sensor and a theoretical one is called the actinity error. Various sensors over- or under-report blue wavelengths while red wavelengths are often under-reported. Correlated Color Temperature (CCT): is a specification of the color appearance of the light emitted by a lamp relating its color to the color of light from a reference source (a blackbody) when heated to a particular temperature, measured in degrees Kelvin (K). The CCT rating for a lamp is a general "warmth" or "coolness" measure of its appearance. However, opposite to the temperature scale, lamps with a CCT rating below 3,200 K are usually considered "warm" sources, while those with a CCT above 4,000 K are usually considered "cool" in appearance. Cosine Correction: A light sensor should be able to accurately measure light at angles to ~90 of normal incidence (0), and a cosine-corrector allows this. Two cosine-correction types exist - one type is a hemispherical plastic diffuser dome (used by Apogee and Spectrum Technologies), while the other is a plastic cylinder (that should rise slightly above its housing in order to properly collect light, which the Li-Cor sensor does). All sensors are advertised to be cosine-corrected, meaning their response will be the same to a beam of light, regardless of that beam's angle of incidence to the sensor (up to a point. Li-Cor advertises their sensor to be correct for light falling at an 80 angle from normal while Apogee states their sensor is ±1% at a 45 angle (from zenith) and ±5% at a 75 degree angle from zenith). Full Width Half Maximum (FWHM): This is an important concept in light measurement. It is simple and easily defined. While the spectral width of the light source could extend for some distance, the maximum is easily determined as is the half-maximum. FWHM is generally used to define peaks and half-maxima of relatively narrow bandwidths (such as LEDs and other 'specialty' cases such as fluorescence). See Figure 2. Figure 2. Full Width Half Maximum (FWHM) is an important concept, especially with narrow bandwidth light sources such as LEDs. In this case, the peak is at 500nm with a FWHM of ~50nm (475-525nm). FWHM is not used for broadband light sources (such as sunlight and most artificial light sources). Let's take an example of why FWHM is important. See Figure 14 - it is the spectral characteristics of a combination of blue and white LEDs. This example would share the FWHM characteristics of a blue LED while ignoring the full spectrum characteristics. Immersion Effect: Reflection of light within a sensor immersed in water is less (relative to a measurement made in air) and results in a greater loss of light. This is due to the refractive indices of plastic and air or water. Hence, more expensive devices (such as the Li-Cor) allow for an 'air' or 'water' calibration to overcome the immersion effect. The Apogee and Spectrum Technologies meters do not offer this option. Integrating Sphere: A device used in measuring light and especially useful when determining flux or spectra of LEDs. Basically, it is a hollow sphere with a diffusive interior coating. Two ports (one for the LED and the other for a light sensor) are at a 90 angle to one another. Lambertian Reflectance: Diffuse reflectance is that which appears to be of the same brightness regardless of the observer's viewing angle. Labsphere's Spectralon (a fluoropolymer) offers an almost ideal Lambertian surface. Barium sulfate is a less expensive - but less Lambertian - material. Light-emitting Diode (LED): A light emitting device consisting of a positive/negative junction where a small amount of electrical current excites metallic compounds doped on a small 'cup'. Photosynthetically Active Radiation (PAR): Light energy powers photosynthesis. This light's bandwidth has been standardized to that electromagnetic energy between 400 and 700nm (violet to red) per area unit (often 1 square meter) per time unit (usually 1 second). PAR is reported as Photosynthetic Photon Flux Density (PPFD) in units of micromole photons per square meter per second (µmol·m²·sec). Reflectance: The ratio of the total amount of radiation, as of light, reflected by a surface to the total amount of radiation incident on the surface. Two pi Sensor; Four pi Sensor: Sensors that collect light only from the direction the sensor is pointed is called 2 pi. A scalar sensor collects light from all directions. A 4 pi scalar sensor resembles an incandescent light bulb. See Figure 3. Figure 3. Two types of Li-Cor PAR sensors. A 2-pi sensor is on the left (like the one used in this report). A 4-pi sensor is to the right. Spectral Responses of Three PAR Sensors Understanding the spectral sensitivities of different PAR sensors is helpful in understanding how accurate measurements will be, especially when dealing with narrow bandwidth light sources, such as LEDs. For our purposes, there are two types of sensors - silicon and gallium arsenide phosphide (GaAsP). The Li-Cor sensor is the silicon type, while the Apogee and FieldScout sensors appear to be made of gallium arsenide phosphide. Figure 4 shows the spectral sensitivity of the Apogee meter, Figure 5 the FieldScout's, and Figure 6 that of the Li-Cor. Unfortunately, Spectrum Technologies does not provide the relative ideal response of their sensor and we therefore must make some assumptions about the actinity errors. Figure 7 is a side-by-side comparison of the Apogee and Li-Cor responses. Figure 4. The Apogee quantum sensor underestimates violet/blue and red wavelengths. Apogee advertises their sensor is responsive to light wavelengths in the range of 409nm to 659nm. After Apogee Instruments' website. Figure 5. Response of the Field Scout Quantum sensor - it appears to be an unfiltered gallium arsenide phosphide (GaAsP)-based photo-sensor. No ideal response information is available. After data on Spectrum Instruments' website. The Apogee meter apparently uses a gallium arsenide phosphide (GaAsP) based sensor with a lens/filter in order to slightly correct the sensor's response. However, it is generally agreed that this type of sensor underestimates violet/blue light (400-500nm) and red wavelengths above 650nm. Figure 6. The Li-Cor quantum sensor underestimates violet (410-420nm) slightly, and red light (690-700nm). This sensor's response is the gold standard in botany/phycology research fields. After data on the Li-Cor website. Figure 7. A comparison of the Apogee and Li-Cor sensors' responses. The Spectrum meter is not included due to little available information on its spectral response in relation to ideal response. Effects of Temperature Apogee's calibrates their quantum sensors at 68F (20C). It reads 0.6 percent high at 50F (10C) and 0.8 percent low at 86F (30C) - see Figure 8. Li-Cor states a change of ± 0.15% per °C (maximum). Figure 8. Effect of temperature on Apogee PAR measurements. Calibration is done at 68F (therefore, 'zero' error). At the temperature of most tropical reef aquaria, the reading would be 0.4-0.5% low. Relative Humidity When making sunlight measurements, the amount of water vapor (humidity) in the atmosphere can cause lower than expected readings. See here for details: http://clearskycalculator.com/model_accuracyPPF.htm#RH Note that all reported measurements were made in the air and the impact of the ultimate humidity - water - will impact meters' responses. 'Sun' and 'Electric' Measurements In the models tested here, Apogee and Spectrum meters offer two measurement modes to overcome deficiencies in the spectral responses of their sensors. Testing revealed that, on average, there is a difference of about 10% between the two modes. However, spectral quality decides which mode is best for a given light source. Our testing begins with: Response of Meters to Sunlight Figures 9 and 10 show the meters' responses to broadband light energy (sunlight, during an overcast morning) and the spectral quality of that light, respectively. As we can see, all meters do a reasonable job of reporting PPFD. Figure 9. A comparison of the Apogee, FieldScout, and Li-Cor sensors' responses to the light field on a cloudy Hawaiian morning. See spectral characteristics in Figure 10. At this intensity, the Apogee reads ~10% high, and the Field Scout reads ~13% when compared to the Li-Cor measurement. Figure 10. Sunlight spectral quality on a cloudy Hawaiian morning. Response of Meters to Individual LEDs As we have seen, each of the PAR meters have done a reasonable job of reporting PAR values of sunlight, even though their sensors' spectral sensitivities vary dramatically. Results of LED testing will now be presented. Blue LEDs Blue LEDs are ubiquitous in lighting designed for reef aquaria and are often combined with LEDs emitting 'white' light ('white' LEDs are blue LEDs to which a phosphor has been added. This phosphor absorbs some of the blue light and fluoresces it in a broad spectrum). Two blue LEDs were examined. See Figures 11 and 12 (notice the differences in the FWHM of the two). Figure 11. This blue LED's output is maximal at 449nm, with a FWHM of ~430-480nm. Figure 12. Acan Lighting's blue LED spectral quality (peak emission at 454nm; FWHM=443-467nm). Analysis of Corrected Color Temperature (CCT) revealed these LEDs were at least 50,000 K (measurements bounced between 50,000 and , or 'off the scale'). The following Figure (13) shows the PAR measurements of the Acan blue LED. Figure 13. Not surprisingly, there are significant differences among the reading of the 3 PAR meters. These are not maximum PAR values. Blue/White LED Combination This combination of LEDs is perhaps the most popular among reef hobbyists, although the ratio of white to blue varies. Figure 14 shows the spectral characteristics of Acan Lighting's LED luminaire (ratio of 2 cool white to 1 'royal' blue). Figure 14. Spectral Power distribution of Acan Lighting's combination of white and blue LEDs. Figure 15. PAR measurements of Acan Lighting's blue/white combination LEDs. These are not maximum PAR values - that was not the goal of the experiment. White LEDs When comparing the spectra of blue and white LEDs, it is easy to see the effects of the phosphors added to a blue LED (these phosphors are the same as those used in broad spectrum fluorescent lamps). White LEDs are often used in combination with 'pure' blue LEDs to mimic the blueness of deeper oceanic waters. See Figure 16. Figure 16. Acan Lighting's white LED spectral quality. Correlated color temperature (CCT) of these LEDs measured 7,300 K which is generally considered to be 'cool white'. Figure 17. PAR values of Acan Lighting's 7,300 K 'cool white' LEDs. No attempt was made to ascertain maximum PAR levels. Cyan (or Aqua) LED Those manufacturers specializing in reef aquaria lighting have recently begun adding variously colored LEDs to their luminaires (interestingly, the first commercially successful LED luminaire, made by PFO Lighting) used green LEDs in addition to blue and white ones). Use of cyan LEDs has a basis when we examined zooxanthellae photo-pigments. Chlorophyll a is sometimes bound with another photo-pigment - peridinin. This complex absorbs light into the green portion of the spectrum and makes it available for photosynthesis. See Figures 18 and 19 for a spectral characteristics and PAR measurements of a cyan LED, respectively. Figure 18. This aqua (or cyan) LED has a maximum output of 505nm, with a FWHM of ~490-525nm. Figure 19. PAR values of a cyan LED as collected in a small integrating sphere. Green LED Many of the comments made about the cyan LEDs would apply to the green LED examined here. The chlorophyll a/peridinin complex can absorb the light emitted by this LED. See Figures 20 and 21. Figure 20. This green LED peaks at 517nm, and has a FWHM of ~495-540nm. Figure 21. Green light (517nm) intensity measured by 3 PAR meters using an integrating sphere. Yellow LED Yellow light is only weakly absorbed by zooxanthellae photo-pigments; however, there is some evidence that yellow light plays a part in intensifying the apparent fluorescence of some orange/red coral pigments. See Figures 22 and 23 for results of testing. Figure 22. Spectral characteristics of the yellow LED with peak output of 595nm and a FWHM of ~587-603nm. Figure 23. PAR values of a yellow LED with a peak emission of 595nm. Taken within an integrating sphere. Red LED Of all the LEDs examined here, those emitting red light are the most controversial. Very little red light is found at depth on natural reefs and it would seem that use of white LEDs (emitting some red light) would satisfy the visual requirements of the hobbyist while supplying more than enough red for photosynthesis. See Riddle, 2003 for effects of too much red light. I'm presently working on the assumption that if a lot of red light is harmful to zooxanthellae, then a lesser amount is proportionally harmful. I am just beginning a project to investigate red light's impact. This will be a part of my presentation at the 2103 MACNA in Florida (www.masna.org). See Figures 24 and 25. Figure 24. This red LED peaks at 647nm (FWHM = ~640-655nm). Figure 25. Comparative measurements of a red LED within an integrating sphere. This completes our observations and analyses of PAR meters and LEDs. Now for our conclusions. Conclusion and Recommendation I decided to write this article after hearing anecdotal comments such as 'PAR meters are useless for measuring LED output' and 'Corals don't survive long-term under LEDs'. The latter has not been my experience, but I really had no idea about the former statement. The concept for this article seemed valid enough and I suspected the article could be written in short order. I had the meters and the LEDs and making the measurements could be made quickly - or so I thought. After writing almost 300 articles for hobbyist-related publications over the course of over 25 years, one might think I would have a good handle on the complexity of a project. In this case, I thought I could research and write the article in 2 or 3 weeks. As it turned out, this work required months of research, construction, measurement, and analyses. The results are complex. To reiterate, we're comparing two relatively inexpensive meters against one costing roughly 10x as much. When measuring sunlight, the Apogee and Spectrum Technologies meters report PAR values that compare favorably to those of the Li-Cor. Additionally, Spectrum Technologies states on their website that their sensor is not useful in making measurements of LEDs (a bit of an overstatement as we shall see). This product evaluation took on added complexity when we consider two of the meters offer two measurement modes - in essence, we are comparing 5 meters, not three. The Apogee and Field Scout meters offer the option of two measuring modes ('Sun' and 'Electric'). This is done in order to offset limitations of the spectral sensitivity of their sensors. The more expensive Li-Cor sensor and meter has no reason to offer this option due to the superior spectral response. Interestingly, the difference in 'Sun' and 'Electric' measurement modes is almost always about 10% (suggesting the difference is simply the result of a preset electronic correction). However, this correction cannot overcome the ability of the sensor to 'see' light. Therefore, Table 1 is offered for those wanting to measure narrow bandwidth light sources such as LEDs. Table 1. Recommended Meter Settings for Various Light Sources. 'X' marks the recommended setting ('Sun' or 'Electric' for the LEDs tested, and 'High' or 'Low' indicate the direction of variation from the reading made by the Li-Cor meter and sensor. The measurement was essentially the same as the Li-Cor product if the box is marked with only an 'X'. Apogee Field Scout LED Sun Electric Sun Electric Blue (450nm) X Low X (Low) Low Blue/White Combo X (Low) Low High X (High) White (7,300 K) X Low High X (High) Cyan (505nm) High X (High) High X (High) Green (517nm) High X (High) High X (High) Yellow (595nm) X (Low) Low High X (High) Red (647nm) X (Low) Low High X (High) Sunlight (Mostly Sunny)* High X (High) High X (High) *Sky Conditions and Sensor Response: As even the most casual observer knows, sky conditions can drastically alter its apparent color composition. The most obvious examples are the yellow 'morning' and orange 'sunset' colors. However, more subtle effects are in play during the day. 'Cloudy' refers to the blue sky and sun being hidden completely by opaque clouds. 'Sunny' conditions exist when no clouds are present. A 'mostly sunny' sky is obscured by no more than 2/8ths opaque clouds. 'Partly sunny' and 'mostly cloudy' means 3/8 to 5/8ths and 6/8 to 7/8ths opaque clouds, respectively. The term 'clear' (as opposed to sunny, naturally enough) is used for nighttime observations. 'Fair' is not a useful meteorological term and should be avoided. 1 The impact of volcanic smoke (vog) on the meters' performance is unknown. Although the measurements were made when conditions were considered to be 'mostly sunny', there is a certain haziness to the sky. Vog is known to absorb some ultraviolet radiation. In addition, there is a considerable amount of seawater aerosols in the air. Simply using the manufacturer's sensor spectra response chart can lead to incorrect conclusions. There were some surprises. It seems to be current wisdom that the Apogee meter under-reports blue light, yet the results of testing showed the meter performed well when in 'sun' measurement mode (while the electric mode read low). Similarly, the Apogee did very well in 'sun' mode when analyzing the output of 7,300 K white LEDs. In addition, the Apogee and FieldScout meters repeatedly performed best when measuring sunlight when in the 'electric' setting. Based on these observations, inexpensive PAR meter have some utility for measuring light produced by LEDs. Lux to PAR Conversion Factors If you have a lux meter, it is possible to convert lux measurements to PAR values. Use these results with some caution - in most cases it would be safe to assume the results will be low. Divide blue (450nm) LED Lux by 69 Divide white (7,300 K) LED Lux by 45 Divide blue (450nm)/white (7,300 K) combination LED (2:1 white/blue ratio) Lux by 67 Technical Notes Spectral analyses were performed by Ocean Optics USB2000â„¢ fiber optic spectrometer and SpectraSuiteâ„¢ software (Ocean Optics, Dunedin, Florida). It took some doing to design and build a workable integrating sphere from scratch (on the order of weeks). Original prototypes were made of papier mâché and were large (6-inch, or ~150mm) diameter, then reduced to 3-inch (76mm). These proved to be too large and did not sufficiently concentrate light. Ultimately, ping pong (table tennis) balls were used. Their exterior were painted white and the interior of the hollow spheres were painted matte white and then coated with barium sulfate (ACS grade) in order to create a surface with good diffuse spectral reflectance characteristics. Barium sulfate was mixed with un-tinted white latex paint (90:10 weight: weight). Two 1/2" (12mm) holes were drilled into the sphere at a 90 angle. An interior baffle was placed adjacent to the sensor port to prevent light from falling directly upon it. Barium sulfate is known to offer good reflectance at ~425 - 700nm. To check this, the barium coating was compared to a diffuse reflectance standard (Labsphere Spectralon WS-1-SL, a fluoropolymer offering a highly Lambertian surface with reflectivity of 99% at 400-1,500nm). See Figure 26 for the reflectance of the barium sulfate coating. Figure 26. Reflectance of the integrating sphere's barium sulfate coating. Reflectance is very good for those spectral sources examined in this article. Ideally, the line should be horizontally flat. This figure shows that violet/blue light is reflected a little less well than other wavelengths. Figure 27 shows the integrating sphere. Figure 27. The 'table tennis ball' integrating sphere. Light from the LED enters from the right (a slight red glow of a red LED can be seen). Light is reflected by the internal barium sulfate surface and is collected at a 90 angle by a PAR sensor (in this case, one manufactured by Li-Cor Biosciences). The integrating sphere would not collect enough light in some cases. To overcome this problem, measurements were made of the high intensity output of a LED luminaire manufactured for aquarium use (Acan Lighting, model 600-18B, Commack, NY). See Figure 28. Figure 28. Acan Lighting's LED luminaire. A sturdy unit - with no fans that can fail! Determination of Correlated Color Temperature (CCT) was determined with an Ocean Optics USB 2000 spectrometer and SpectraSuite software. In order to do so, the spectrometer's measurements must be calibrated to a known source. To this end, an Ocean Optics' LS-1-Cal tungsten halogen NIST-traceable light source was used. This light source had little use on it and total hours fell well below the cutoff of 50 hours (when re-calibration is required). Settings of the software included a setting for 'emissive' color (that emitted by a light source such as a LED) and 2 Observer (photopic, daylight observer). Lux measurements were made using a Gossen Luna Pro lux meter (Gossen Foto-und Lichtmesstechnik GmbH, Nürnberg, Germany). Calibration Apogee recommends calibration of their meters ever 3 years, while Li-Cor recommends every 2 years. The Apogee meter has not been calibrated since purchase. The Li-Cor LI-1400 data logger is new and its sensor was rebuilt about 5 years ago. To check if your PAR meter needs re-calibration, see this site: http://clearskycalculator.com/longitudeTZ.htm Note: This calculator works if the sky is truly clear. It did not perform well here in Hawaii due to the amount of 'vog' from the continuing volcanic eruption. References Kirk, J.T.O., 2000. Light and Photosynthesis in Aquatic Ecosystems. Cambridge University Press, Cambridge, United Kingdom. 509pp. Riddle, D., 2005. Product Review: A Comparison of Two Quantum Meters- Li-Cor v. Apogee. http://www.advancedaquarist.com/2005/7/review Riddle, D., 2003. Effects of narrow bandwidth light sources on coral host and zooxanthellae pigments. http://www.advancedaquarist.com/2003/11/aafeature View the full article

Click through to see the images. It was 2005 when I last wrote an article presenting results of a comparison between Photosynthetically Active Radiation (PAR) meters, and the lamps used during testing were metal halides of various kelvin ratings (see Riddle, 2007). In those days, the use of light-emitting diodes (LEDs) for aquaria was something discussed by only a few. Nowadays, use of metal halide lamps is much less popular and usually seen over larger aquaria or those of die-hard fans, yet, to my knowledge, there have been no updates on the utility of different brand PAR meters and their responses when judging output of LEDs. This article will compare the responses of three quantum meters when measuring LED light output. Specifically, these are meters manufactured by Apogee Instrumentsâ„¢ (model QMSW-SS; Logan, Utah), Li-Cor Biosciencesâ„¢ (LI-1400 datalogger and LI-189 sensor; Lincoln, Nebraska) and Spectrum Technologiesâ„¢ (FieldScout; Plainfield, Illinois). Product Details Li-Cor LI-1400 Quantum Meter and LI-189 Sensor Li-Cor Biosciences (Lincoln, Nebraska, USA) is noted for quality instruments, and their meter/sensor combinations have gained wide acceptance within the scientific community. Quality comes at a price (the referenced combination currently costs more than $3,000). The sensor construction is an intricate one - see Figure 1. In addition, the sensor is relatively large and the cord exits the bottom. These facts restrict its use to larger aquaria. Figure 1. Typical construction of an expensive PAR sensor, such as Li-Cor's. From Kirk, 2000. Apogee Quantum Meter Apogee Instruments (Logan, Utah, USA) manufactures entry-level PAR meters and sensors, and many hobbyists have found favor with them due to their affordability. The sensor is relatively small and its cord exits the side making it ideal for use in tight quarters (such as aquaria). FieldScout Quantum Meter Spectrum Technologies (Plainfield, Illinois, USA) manufacturers a number of products aimed at the agricultural/horticultural markets. Although the meter tested here is the FieldScout Light Meter, the sensors are interchangeable with other Spectrum products (such as their wonderful WatchDog datalogger). The sensor tested here was custom-built for my lab for use when testing artificial light sources. Spectrum does not recommend their quantum sensor for use with LEDs but I wondered just how much of an error there actually is, hence I have included it in this review. In all fairness, we're comparing an expensive instrument (the Li-Cor setup costing over $3,000) to relatively inexpensive ($300-$400 or so) units. A calibrated light source would be needed to accurately judge the responses of all three meters. This luxury was not available for this review, hence the Li-Cor meter - based on the advertised responses of all three meters - will be considered 'correct'. There are several things that can affect a quantum meter's reading, these include: Spectral sensitivity of the sensor Spectral quality of the light Sensor Cosine Correction Sensor Construction (2 pi or 4 pi) Testing medium (air, water, etc.) Condition of the sensor (physical damage, age - 'fogging' of optical components, cleanliness) Sensor/meter calibration Temperature Light source used for calibration by the manufacturer These terms will be used throughout this article: Glossary Actinity Error: A perfect PAR sensor would be equally responsive to all wavelengths of light between 400nm and 700nm. In practice, this is not possible and response difference between a real sensor and a theoretical one is called the actinity error. Various sensors over- or under-report blue wavelengths while red wavelengths are often under-reported. Correlated Color Temperature (CCT): is a specification of the color appearance of the light emitted by a lamp relating its color to the color of light from a reference source (a blackbody) when heated to a particular temperature, measured in degrees Kelvin (K). The CCT rating for a lamp is a general "warmth" or "coolness" measure of its appearance. However, opposite to the temperature scale, lamps with a CCT rating below 3,200 K are usually considered "warm" sources, while those with a CCT above 4,000 K are usually considered "cool" in appearance. Cosine Correction: A light sensor should be able to accurately measure light at angles to ~90 of normal incidence (0), and a cosine-corrector allows this. Two cosine-correction types exist - one type is a hemispherical plastic diffuser dome (used by Apogee and Spectrum Technologies), while the other is a plastic cylinder (that should rise slightly above its housing in order to properly collect light, which the Li-Cor sensor does). All sensors are advertised to be cosine-corrected, meaning their response will be the same to a beam of light, regardless of that beam's angle of incidence to the sensor (up to a point. Li-Cor advertises their sensor to be correct for light falling at an 80 angle from normal while Apogee states their sensor is ±1% at a 45 angle (from zenith) and ±5% at a 75 degree angle from zenith). Full Width Half Maximum (FWHM): This is an important concept in light measurement. It is simple and easily defined. While the spectral width of the light source could extend for some distance, the maximum is easily determined as is the half-maximum. FWHM is generally used to define peaks and half-maxima of relatively narrow bandwidths (such as LEDs and other 'specialty' cases such as fluorescence). See Figure 2. Figure 2. Full Width Half Maximum (FWHM) is an important concept, especially with narrow bandwidth light sources such as LEDs. In this case, the peak is at 500nm with a FWHM of ~50nm (475-525nm). FWHM is not used for broadband light sources (such as sunlight and most artificial light sources). Let's take an example of why FWHM is important. See Figure 14 - it is the spectral characteristics of a combination of blue and white LEDs. This example would share the FWHM characteristics of a blue LED while ignoring the full spectrum characteristics. Immersion Effect: Reflection of light within a sensor immersed in water is less (relative to a measurement made in air) and results in a greater loss of light. This is due to the refractive indices of plastic and air or water. Hence, more expensive devices (such as the Li-Cor) allow for an 'air' or 'water' calibration to overcome the immersion effect. The Apogee and Spectrum Technologies meters do not offer this option. Integrating Sphere: A device used in measuring light and especially useful when determining flux or spectra of LEDs. Basically, it is a hollow sphere with a diffusive interior coating. Two ports (one for the LED and the other for a light sensor) are at a 90 angle to one another. Lambertian Reflectance: Diffuse reflectance is that which appears to be of the same brightness regardless of the observer's viewing angle. Labsphere's Spectralon (a fluoropolymer) offers an almost ideal Lambertian surface. Barium sulfate is a less expensive - but less Lambertian - material. Light-emitting Diode (LED): A light emitting device consisting of a positive/negative junction where a small amount of electrical current excites metallic compounds doped on a small 'cup'. Photosynthetically Active Radiation (PAR): Light energy powers photosynthesis. This light's bandwidth has been standardized to that electromagnetic energy between 400 and 700nm (violet to red) per area unit (often 1 square meter) per time unit (usually 1 second). PAR is reported as Photosynthetic Photon Flux Density (PPFD) in units of micromole photons per square meter per second (µmol·m²·sec). Reflectance: The ratio of the total amount of radiation, as of light, reflected by a surface to the total amount of radiation incident on the surface. Two pi Sensor; Four pi Sensor: Sensors that collect light only from the direction the sensor is pointed is called 2 pi. A scalar sensor collects light from all directions. A 4 pi scalar sensor resembles an incandescent light bulb. See Figure 3. Figure 3. Two types of Li-Cor PAR sensors. A 2-pi sensor is on the left (like the one used in this report). A 4-pi sensor is to the right. Spectral Responses of Three PAR Sensors Understanding the spectral sensitivities of different PAR sensors is helpful in understanding how accurate measurements will be, especially when dealing with narrow bandwidth light sources, such as LEDs. For our purposes, there are two types of sensors - silicon and gallium arsenide phosphide (GaAsP). The Li-Cor sensor is the silicon type, while the Apogee and FieldScout sensors appear to be made of gallium arsenide phosphide. Figure 4 shows the spectral sensitivity of the Apogee meter, Figure 5 the FieldScout's, and Figure 6 that of the Li-Cor. Unfortunately, Spectrum Technologies does not provide the relative ideal response of their sensor and we therefore must make some assumptions about the actinity errors. Figure 7 is a side-by-side comparison of the Apogee and Li-Cor responses. Figure 4. The Apogee quantum sensor underestimates violet/blue and red wavelengths. Apogee advertises their sensor is responsive to light wavelengths in the range of 409nm to 659nm. After Apogee Instruments' website. Figure 5. Response of the Field Scout Quantum sensor - it appears to be an unfiltered gallium arsenide phosphide (GaAsP)-based photo-sensor. No ideal response information is available. After data on Spectrum Instruments' website. The Apogee meter apparently uses a gallium arsenide phosphide (GaAsP) based sensor with a lens/filter in order to slightly correct the sensor's response. However, it is generally agreed that this type of sensor underestimates violet/blue light (400-500nm) and red wavelengths above 650nm. Figure 6. The Li-Cor quantum sensor underestimates violet (410-420nm) slightly, and red light (690-700nm). This sensor's response is the gold standard in botany/phycology research fields. After data on the Li-Cor website. Figure 7. A comparison of the Apogee and Li-Cor sensors' responses. The Spectrum meter is not included due to little available information on its spectral response in relation to ideal response. Effects of Temperature Apogee's calibrates their quantum sensors at 68F (20C). It reads 0.6 percent high at 50F (10C) and 0.8 percent low at 86F (30C) - see Figure 8. Li-Cor states a change of ± 0.15% per °C (maximum). Figure 8. Effect of temperature on Apogee PAR measurements. Calibration is done at 68F (therefore, 'zero' error). At the temperature of most tropical reef aquaria, the reading would be 0.4-0.5% low. Relative Humidity When making sunlight measurements, the amount of water vapor (humidity) in the atmosphere can cause lower than expected readings. See here for details: http://clearskycalculator.com/model_accuracyPPF.htm#RH Note that all reported measurements were made in the air and the impact of the ultimate humidity - water - will impact meters' responses. 'Sun' and 'Electric' Measurements In the models tested here, Apogee and Spectrum meters offer two measurement modes to overcome deficiencies in the spectral responses of their sensors. Testing revealed that, on average, there is a difference of about 10% between the two modes. However, spectral quality decides which mode is best for a given light source. Our testing begins with: Response of Meters to Sunlight Figures 9 and 10 show the meters' responses to broadband light energy (sunlight, during an overcast morning) and the spectral quality of that light, respectively. As we can see, all meters do a reasonable job of reporting PPFD. Figure 9. A comparison of the Apogee, FieldScout, and Li-Cor sensors' responses to the light field on a cloudy Hawaiian morning. See spectral characteristics in Figure 10. At this intensity, the Apogee reads ~10% high, and the Field Scout reads ~13% when compared to the Li-Cor measurement. Figure 10. Sunlight spectral quality on a cloudy Hawaiian morning. Response of Meters to Individual LEDs As we have seen, each of the PAR meters have done a reasonable job of reporting PAR values of sunlight, even though their sensors' spectral sensitivities vary dramatically. Results of LED testing will now be presented. Blue LEDs Blue LEDs are ubiquitous in lighting designed for reef aquaria and are often combined with LEDs emitting 'white' light ('white' LEDs are blue LEDs to which a phosphor has been added. This phosphor absorbs some of the blue light and fluoresces it in a broad spectrum). Two blue LEDs were examined. See Figures 11 and 12 (notice the differences in the FWHM of the two). Figure 11. This blue LED's output is maximal at 449nm, with a FWHM of ~430-480nm. Figure 12. Acan Lighting's blue LED spectral quality (peak emission at 454nm; FWHM=443-467nm). Analysis of Corrected Color Temperature (CCT) revealed these LEDs were at least 50,000 K (measurements bounced between 50,000 and , or 'off the scale'). The following Figure (13) shows the PAR measurements of the Acan blue LED. Figure 13. Not surprisingly, there are significant differences among the reading of the 3 PAR meters. These are not maximum PAR values. Blue/White LED Combination This combination of LEDs is perhaps the most popular among reef hobbyists, although the ratio of white to blue varies. Figure 14 shows the spectral characteristics of Acan Lighting's LED luminaire (ratio of 2 cool white to 1 'royal' blue). Figure 14. Spectral Power distribution of Acan Lighting's combination of white and blue LEDs. Figure 15. PAR measurements of Acan Lighting's blue/white combination LEDs. These are not maximum PAR values - that was not the goal of the experiment. White LEDs When comparing the spectra of blue and white LEDs, it is easy to see the effects of the phosphors added to a blue LED (these phosphors are the same as those used in broad spectrum fluorescent lamps). White LEDs are often used in combination with 'pure' blue LEDs to mimic the blueness of deeper oceanic waters. See Figure 16. Figure 16. Acan Lighting's white LED spectral quality. Correlated color temperature (CCT) of these LEDs measured 7,300 K which is generally considered to be 'cool white'. Figure 17. PAR values of Acan Lighting's 7,300 K 'cool white' LEDs. No attempt was made to ascertain maximum PAR levels. Cyan (or Aqua) LED Those manufacturers specializing in reef aquaria lighting have recently begun adding variously colored LEDs to their luminaires (interestingly, the first commercially successful LED luminaire, made by PFO Lighting) used green LEDs in addition to blue and white ones). Use of cyan LEDs has a basis when we examined zooxanthellae photo-pigments. Chlorophyll a is sometimes bound with another photo-pigment - peridinin. This complex absorbs light into the green portion of the spectrum and makes it available for photosynthesis. See Figures 18 and 19 for a spectral characteristics and PAR measurements of a cyan LED, respectively. Figure 18. This aqua (or cyan) LED has a maximum output of 505nm, with a FWHM of ~490-525nm. Figure 19. PAR values of a cyan LED as collected in a small integrating sphere. Green LED Many of the comments made about the cyan LEDs would apply to the green LED examined here. The chlorophyll a/peridinin complex can absorb the light emitted by this LED. See Figures 20 and 21. Figure 20. This green LED peaks at 517nm, and has a FWHM of ~495-540nm. Figure 21. Green light (517nm) intensity measured by 3 PAR meters using an integrating sphere. Yellow LED Yellow light is only weakly absorbed by zooxanthellae photo-pigments; however, there is some evidence that yellow light plays a part in intensifying the apparent fluorescence of some orange/red coral pigments. See Figures 22 and 23 for results of testing. Figure 22. Spectral characteristics of the yellow LED with peak output of 595nm and a FWHM of ~587-603nm. Figure 23. PAR values of a yellow LED with a peak emission of 595nm. Taken within an integrating sphere. Red LED Of all the LEDs examined here, those emitting red light are the most controversial. Very little red light is found at depth on natural reefs and it would seem that use of white LEDs (emitting some red light) would satisfy the visual requirements of the hobbyist while supplying more than enough red for photosynthesis. See Riddle, 2003 for effects of too much red light. I'm presently working on the assumption that if a lot of red light is harmful to zooxanthellae, then a lesser amount is proportionally harmful. I am just beginning a project to investigate red light's impact. This will be a part of my presentation at the 2103 MACNA in Florida (www.masna.org). See Figures 24 and 25. Figure 24. This red LED peaks at 647nm (FWHM = ~640-655nm). Figure 25. Comparative measurements of a red LED within an integrating sphere. This completes our observations and analyses of PAR meters and LEDs. Now for our conclusions. Conclusion and Recommendation I decided to write this article after hearing anecdotal comments such as 'PAR meters are useless for measuring LED output' and 'Corals don't survive long-term under LEDs'. The latter has not been my experience, but I really had no idea about the former statement. The concept for this article seemed valid enough and I suspected the article could be written in short order. I had the meters and the LEDs and making the measurements could be made quickly - or so I thought. After writing almost 300 articles for hobbyist-related publications over the course of over 25 years, one might think I would have a good handle on the complexity of a project. In this case, I thought I could research and write the article in 2 or 3 weeks. As it turned out, this work required months of research, construction, measurement, and analyses. The results are complex. To reiterate, we're comparing two relatively inexpensive meters against one costing roughly 10x as much. When measuring sunlight, the Apogee and Spectrum Technologies meters report PAR values that compare favorably to those of the Li-Cor. Additionally, Spectrum Technologies states on their website that their sensor is not useful in making measurements of LEDs (a bit of an overstatement as we shall see). This product evaluation took on added complexity when we consider two of the meters offer two measurement modes - in essence, we are comparing 5 meters, not three. The Apogee and Field Scout meters offer the option of two measuring modes ('Sun' and 'Electric'). This is done in order to offset limitations of the spectral sensitivity of their sensors. The more expensive Li-Cor sensor and meter has no reason to offer this option due to the superior spectral response. Interestingly, the difference in 'Sun' and 'Electric' measurement modes is almost always about 10% (suggesting the difference is simply the result of a preset electronic correction). However, this correction cannot overcome the ability of the sensor to 'see' light. Therefore, Table 1 is offered for those wanting to measure narrow bandwidth light sources such as LEDs. Table 1. Recommended Meter Settings for Various Light Sources. 'X' marks the recommended setting ('Sun' or 'Electric' for the LEDs tested, and 'High' or 'Low' indicate the direction of variation from the reading made by the Li-Cor meter and sensor. The measurement was essentially the same as the Li-Cor product if the box is marked with only an 'X'. Apogee Field Scout LED Sun Electric Sun Electric Blue (450nm) X Low X (Low) Low Blue/White Combo X (Low) Low High X (High) White (7,300 K) X Low High X (High) Cyan (505nm) High X (High) High X (High) Green (517nm) High X (High) High X (High) Yellow (595nm) X (Low) Low High X (High) Red (647nm) X (Low) Low High X (High) Sunlight (Mostly Sunny)* High X (High) High X (High) *Sky Conditions and Sensor Response: As even the most casual observer knows, sky conditions can drastically alter its apparent color composition. The most obvious examples are the yellow 'morning' and orange 'sunset' colors. However, more subtle effects are in play during the day. 'Cloudy' refers to the blue sky and sun being hidden completely by opaque clouds. 'Sunny' conditions exist when no clouds are present. A 'mostly sunny' sky is obscured by no more than 2/8ths opaque clouds. 'Partly sunny' and 'mostly cloudy' means 3/8 to 5/8ths and 6/8 to 7/8ths opaque clouds, respectively. The term 'clear' (as opposed to sunny, naturally enough) is used for nighttime observations. 'Fair' is not a useful meteorological term and should be avoided. 1 The impact of volcanic smoke (vog) on the meters' performance is unknown. Although the measurements were made when conditions were considered to be 'mostly sunny', there is a certain haziness to the sky. Vog is known to absorb some ultraviolet radiation. In addition, there is a considerable amount of seawater aerosols in the air. Simply using the manufacturer's sensor spectra response chart can lead to incorrect conclusions. There were some surprises. It seems to be current wisdom that the Apogee meter under-reports blue light, yet the results of testing showed the meter performed well when in 'sun' measurement mode (while the electric mode read low). Similarly, the Apogee did very well in 'sun' mode when analyzing the output of 7,300 K white LEDs. In addition, the Apogee and FieldScout meters repeatedly performed best when measuring sunlight when in the 'electric' setting. Based on these observations, inexpensive PAR meter have some utility for measuring light produced by LEDs. Lux to PAR Conversion Factors If you have a lux meter, it is possible to convert lux measurements to PAR values. Use these results with some caution - in most cases it would be safe to assume the results will be low. Divide blue (450nm) LED Lux by 69 Divide white (7,300 K) LED Lux by 45 Divide blue (450nm)/white (7,300 K) combination LED (2:1 white/blue ratio) Lux by 67 Technical Notes Spectral analyses were performed by Ocean Optics USB2000â„¢ fiber optic spectrometer and SpectraSuiteâ„¢ software (Ocean Optics, Dunedin, Florida). It took some doing to design and build a workable integrating sphere from scratch (on the order of weeks). Original prototypes were made of papier mâché and were large (6-inch, or ~150mm) diameter, then reduced to 3-inch (76mm). These proved to be too large and did not sufficiently concentrate light. Ultimately, ping pong (table tennis) balls were used. Their exterior were painted white and the interior of the hollow spheres were painted matte white and then coated with barium sulfate (ACS grade) in order to create a surface with good diffuse spectral reflectance characteristics. Barium sulfate was mixed with un-tinted white latex paint (90:10 weight: weight). Two 1/2" (12mm) holes were drilled into the sphere at a 90 angle. An interior baffle was placed adjacent to the sensor port to prevent light from falling directly upon it. Barium sulfate is known to offer good reflectance at ~425 - 700nm. To check this, the barium coating was compared to a diffuse reflectance standard (Labsphere Spectralon WS-1-SL, a fluoropolymer offering a highly Lambertian surface with reflectivity of 99% at 400-1,500nm). See Figure 26 for the reflectance of the barium sulfate coating. Figure 26. Reflectance of the integrating sphere's barium sulfate coating. Reflectance is very good for those spectral sources examined in this article. Ideally, the line should be horizontally flat. This figure shows that violet/blue light is reflected a little less well than other wavelengths. Figure 27 shows the integrating sphere. Figure 27. The 'table tennis ball' integrating sphere. Light from the LED enters from the right (a slight red glow of a red LED can be seen). Light is reflected by the internal barium sulfate surface and is collected at a 90 angle by a PAR sensor (in this case, one manufactured by Li-Cor Biosciences). The integrating sphere would not collect enough light in some cases. To overcome this problem, measurements were made of the high intensity output of a LED luminaire manufactured for aquarium use (Acan Lighting, model 600-18B, Commack, NY). See Figure 28. Figure 28. Acan Lighting's LED luminaire. A sturdy unit - with no fans that can fail! Determination of Correlated Color Temperature (CCT) was determined with an Ocean Optics USB 2000 spectrometer and SpectraSuite software. In order to do so, the spectrometer's measurements must be calibrated to a known source. To this end, an Ocean Optics' LS-1-Cal tungsten halogen NIST-traceable light source was used. This light source had little use on it and total hours fell well below the cutoff of 50 hours (when re-calibration is required). Settings of the software included a setting for 'emissive' color (that emitted by a light source such as a LED) and 2 Observer (photopic, daylight observer). Lux measurements were made using a Gossen Luna Pro lux meter (Gossen Foto-und Lichtmesstechnik GmbH, Nürnberg, Germany). Calibration Apogee recommends calibration of their meters ever 3 years, while Li-Cor recommends every 2 years. The Apogee meter has not been calibrated since purchase. The Li-Cor LI-1400 data logger is new and its sensor was rebuilt about 5 years ago. To check if your PAR meter needs re-calibration, see this site: http://clearskycalculator.com/longitudeTZ.htm Note: This calculator works if the sky is truly clear. It did not perform well here in Hawaii due to the amount of 'vog' from the continuing volcanic eruption. References Kirk, J.T.O., 2000. Light and Photosynthesis in Aquatic Ecosystems. Cambridge University Press, Cambridge, United Kingdom. 509pp. Riddle, D., 2005. Product Review: A Comparison of Two Quantum Meters- Li-Cor v. Apogee. http://www.advancedaquarist.com/2005/7/review Riddle, D., 2003. Effects of narrow bandwidth light sources on coral host and zooxanthellae pigments. http://www.advancedaquarist.com/2003/11/aafeature View the full article

Click through to see the images. My name is Paul Bruns and I live in Bridgewater Massachussetts. It is quite an honor to have my aquarium featured here in Advanced Aquarist. I have been keeping aquaria in one form or another for over 40 years so it's a thrill for me to be asked to display my reef here. Since its setup almost eight years ago there have been many changes to my system and reef . In this write up I will try to explain what I have done and why. I also hope to convey the wonder and great pleasure I experience with this hobby. Some Background My reefkeeping philosophy can be summed up as having two priorities. First and foremost is the welfare and health of the animals under my care. I would do almost anything for them. Secondly, I like to pay a lot of attention to the aesthetics, beauty and presentation of the aquarium to make the viewing experience the best I can make it. I know that the main focus should ultimately be about what is inside the tank. However, I think the appearance of the entire setup and the room it is located in can have a big impact on the viewer. As the aquarium is in the middle of my home I think this is very important. My present system is the product of what I learned from the many that came before it. I used that experience to create what I think is a unique viewing experience of a beautiful reef in an unconventional room. The Tank The tank itself is 427 gallons. It is eurobraced acrylic with a center overflow made by Invisions Inc. The tank measures 84" x 36" x 29". The center overflow allows for unobstructed viewing from all angles of the room. Building the stand was a challenge because I generally dislike the look of all conventional aquarium stands. I wanted something that I could see through and would not appear boxy. The stand is made of 4 columns of cinderblock topped with 3 steel I beams and 3/4" plywood. The columns and sides were tiled over with the same tile used for the floor of the room. This helps the stand fade from view instead of standing out. I have had guests jump with shock when one of my dogs comes walking out from under the stand to say hello. All the plumbing and electrical are routed through the legs of the stand to the sump in the basement below. Filtration I don't think there is any kind of aquarium filtration method I haven't tried or used. All are useful and have their applications. I have found that no single method alone of nutrient control is sufficient to handle the bioload of my reef. I have gone through a progression of methodologies over the past eight years. I used ozone for a while but found keeping the air dry for it problematic. I had a remote deep sand bed when I originally set up the system. At around the second year nitrates began to rise and I realized this method of nitrate control just wasn't working anymore. I switched to vodka dosing and bought a sulfur denitrator. That worked, but what a pain! Daily additions of vodka were tedious. The reactor worked well but I didn't like the adjustments I had to make to it as nitrate levels of the water fluctuated. I also had a persistent problem with phosphates. I used GFO and dripped lanthanum chloride into filter socks and a diatom filter. GFO was expensive and often caused STN on my acros when I changed them. Lanthanum dosing was a real chore. Through a lot of experimentation and lots of trial and error I eventually found success. A combination of a good skimmer, carbon dosing (biopellets) and an Algae Turf Scrubber keeps the nutrient levels of my water very low. I can feed large amounts of food without worry. The skimmer is a Bubble King 250 Internal. The biopellets tumble in a NextReef reactor. The algae Turf Scrubber I made myself. Lighting Originally I had two Maristar fixtures with four 250 watt halides and four 39 watt T5s. I also used some 12" Finnex T5 fixtures to try and light up some of the darker areas of the tank. This lighting configuration was used for 6 years. It was not entirely successful as there were dimly lit areas of the tank and all those fixtures hanging above looked pretty poor. In 2011 I upgraded the lighting to 12 Aqua Illuminations Sol Blues. Since that time I have added 2 more. The difference has been dramatic for my corals and the overall look of the tank and room were remarkably enhanced. I have some advise for anyone that is thinking of changing to LED lighting. Measure the intensity of your present system with a par meter or lux meter. I used a lux meter. When you put up your LEDs, match that intensity as best you can and slowly change from there. Circulation There are five Tunze Stream Pumps. Three are attached to Vertex Moceans that sweep back and forth across areas that are mostly populated with SPS. Three others are in fixed positions. All are mounted on the center overflow. The return pump is a Reeflow Goby Gold and is located with the sump in the basement. Temperature control Believe it or not, cooling has never been a big issue, even in a sunroom. When the temperature of the water reaches 80.0F, a fan on the wall adjacent to the tank blows air across the surface of the water. Even with the air temp of the room at 86F, the tank temp has not exceeded 80.2F. With the new AI lighting, the room stays a lot cooler and the AC runs a lot less. There are two 500watt titanium heaters in the sump for heating. In the winter the sump and everything I can reach are insulated. Calcium and Alkalinity I utilize both a calcium reactor and a kalk stirrer to keep up with the demand. The calcium reactor is made by Schuran and the kalk reactor by Aqua Medic. A Spectrapure LitreMeter pulls RO/DI water through the kalk reactor for all top-off. Controllers I have an Apex Lite controller but this is relatively new and is not completely configured. It presently controls the heaters, the cooling fan, the lights on the ATS and some air pumps. I will get an e-mail and text message if the power fails or if the pH or temperature go out of range. The specific gravity and top- off are controlled by the SeaVisions Dialyseas, which is described next. Maintenance I thought a lot about maintenance when I was planning this tank. I ended up buying a Dialyseas made by Seavisons. I was very tired of doing water changes and I knew a tank of this size would need sizable and frequent ones. The Dialyseas does all the water changes for me. I just add the salt of my choice to the brine bucket. I can set how much water I want changed on a daily basis. Right now I have it set low, only 1.5 gallons a day. The Dialyseas also makes all the RO/DI water I need and monitors the specific gravity with a conductivity meter. It makes adjustments when needed and is amazingly stable and accurate. Here is a link to a vid that shows the basement sump and equipment. The algae turf scrubber is scraped once weekly, usually on the weekend. I get a large dinner-plate full of algae every week. I replace 2 cups of carbon in the carbon reactor (an old converted calcium reactor) every third week. I add one large spoonful of calcium hydroxide to the kalk stirrer every night. I clean the acrylic almost every day, but that is because I have OCD when it comes to my tank. The Tunze powerheads get bleached and vinegar dipped when needed. Additives Lugols Iodine, 8 drops daily. Feeding A sheet of nori and a cube of cyclops are fed in the moring while I have my coffee. At 10 AM, 5PM and 8PM an automated feeder dispenses various pelletized dry foods. Around 2 PM I feed 10 cubes of frozen mysis and one cube of cyclops. Livestock Fish Anthias 2 Bartlets 2 Squarespot 3 Dispar 6 Evansi Pseudochromis 1 Royal Dottyback Cardinalfish 1 Bluestreak Cardinalfish 1 Pajama Cardinalfish 2 Banggai Cardinalfish (pair) Butterflyfish 1 Copperbanded Butterfly Angelfish 3 Coral Beauty (Centropyge bispinosa) 1 Lemarcks Angelfish (Genicanthus lamarck) Damselfish/Clownfish 1 Ocellaris Anemonefish (Amphiprion ocellaris) 5 Pink Skunk Anemonefish (Amphiprion perideraion) 6 Blue Green Chromis (Chromis viridis) 2 Lemon Damselfish (Pomecentrus moluccensis) 1 Allen's Damselfish (Pomacentrus alleni) Wrasses 1 Redfinn Fairy Wrasse (Cirrhilabrus rubripinnis) 1 Golden Wrasse (Halichoeres chrysus) 1 Neon Wrasse ( Halichoeres melanurus) 1 Leopard Wrasse (Macropharyngodon meleagris) 1 Carpenters Flasher Wrasse (Paracheilinus carpenteri) 1 Dusky Wrasse (Halichoeres marginatus) Blennies 1 Midas Blenny (Ecsenius midas) Dragonets 2 Green Mandarinfish (Synchiropus splendidus) Gobies Pair Longfinned or Diamondback Sleeper Goby Rabbitfish 1 Foxface Rabbitfish (Siganus unimaculatus) Triggerfish 1 pair of Bluethroat Triggerfish ( Xanthichthys auromarginatus) Both my Rabbitfish and my Hippo Tang lost parts of their fins on their introduction to the tank. I do not know what the cause was, and neither fish regained what was lost. The Hippo Tang is the Edward Scissorhands of the reef and looks like he went through a blender. He is very healthy though and continues to grow. My Bluethroat Triggerfish are my favorite and exhibit the most personality. The male follows me around the room and I swear he's smiling at me. Corals I'm not going to attempt to list all the corals present in my tank. Suffice it to say that it is a mixed reef with softies, gorgonians, and many SPS. Reefers who keep careful track of all the corals they place in their systems have my due admiration. Someday I will get around to cataloging them all. Right now I can say that I try to achieve the most diversity that I can. That is the goal and my challenge. Inverts 1 large S. gigantea anemone 1 green curly cue anemone 1 golden tear-drop T.maxima clam 2 T.crocea clams 1 very large black sea cucumber Various shrimps, crabs and snails Issues No reef tank endeavor would be complete without experiencing some of the common problems we all suffer through. I think I have had my fair share of all the plagues that are common to this hobby. Everything from cyano to red bugs, I have met them all. I have had AEFW present in the main display since at least 2008 and probably well before that. I control them now with wrasses and a turkey baster. I cannot detect any damage to my corals, but I'm sure there would be if I let their populations increase. The worst effect of their presence is that I do not give out or sell any acro frags. Another problem is that I find that the reef gets crowded very fast. I love to buy corals and I want to have as much diversity as I can manage. Also of course everything grows. The challenge is to arrange everything in such a way so that the reef doesn't look like a big block. I am continuously moving things around and adjusting the aquascape. Reefkeeping is very much like gardening. There is lots of pruning and transplanting. As a result there is usually an area somewhere in the reef where things look new with young frags and recently acquired corals. I have documented the many transformations with videos on YouTube. You can see these videos here: http://www.youtube.com/user/reefkeeper2/videos?flow=grid&view=0 Water Parameters I have listed the water parameters but the only testing I do on a regular basis is for alkalinity and iodine. Temperature: 78.4-80.0F pH: 7.9-8.3 Specific Gravity: 1.025 Ammonia: non-detectable Nitrite: non-detectable Nitrate: non-detectable Phosphate: 0.01- 0.03ppm Calcium: 450ppm KH: 8.2 Magnesium: 1500ppm Equipment list Skimmer: Bubble King 250 Internal Pumps: Return pump is a Reeflow Goby Gold. Circulation pumps are Tunze Streams Heaters: 2 Finnex 500 watt heaters Calcium Reactor: Schuran Calcium Reactor Kalk Stirrer: Aqua Medic Kalk Stirrer Auto Feeder: Eheim Auto Fish Feeder for pelletized foods Control System: Seavisions Dialyseas for water changes and control of specific gravity. Apex controller is used for heating, cooling, lighting of the ATS and alarms. Lights: 14 Aqua Illuminations Sol Blues Top off: Liter Meter III RO Unit: Dialyseas Other: Next Reef Reactors for biopellets Conclusion I really love this hobby. There are so many different facets to it that keep you engaged and interested. If you are a tech geek, a biologist, chemist, a photographer or just someone that appreciates great natural beauty, there is something here for you. I never seem to tire of it. I would like to thank Leonard Ho for asking me to display my aquarium here. I would also like to thank Greg Thevenin for his tremendous help with the photography, and all of my friends and fellow reefers of the Boston Reefers Society who have made this hobby even more enjoyable for me. Here is a small sampling of the 100+ photos of Paul Bruns' Feature Aquarium photo album. Click on the "view FEATURE AQUARIUM photo album" link below to see all the photos. View the full article

Click through to see the images. Sharksucker fish (Remora spp.) are the fish you see stuck to the underside of larger fish, typically sharks, using a special sucker disk on the top of its head. Scientists have long speculated on what this sucker actually is and how it developed. The Natural History Museum's website has an interesting piece on the sucker development and it turns out the sucker is actually a modified dorsal fin. To find out this information, Ralf Britz of the Natural History Museum and David Johnson of the Smithsonian National Museum of Natural History studied the development stages of larval suckerfish using a bone-staining method, which stains the bones different shades of pink and purple. As the larval Remora developed, they watched the dorsal fin area and were surprised to see it start out as a normal dorsal fin. By the time the larvae reached 30mm in length, the dorsal fin had migrated toward the head and formed a perfect 2mm sucker. So it turns out the fish has not evolved a completely new structure, it is just a modification of an existing structure. View the full article

Click through to see the images. We're also happy to announce a new Advanced Aquarist Featured Aquarium article publishing tomorrow, Jan 30, 2013. It's been a while since we've featured a reader's reef system, but trust us when we say tomorrow's article is worth the wait. In the meanwhile, let us whet your appetite with a beautiful aquarium that comes to us from Poland. Set the video to 720p HD for maximum enjoyment. " height="383" type="application/x-shockwave-flash" width="640"> "> "> View the full article