sherman

Waiting for parts to be in

That is all the day.

Natural illumination Natural illumination under water is not sufficient for photosynthesis until the sun rises approximately 15 degrees over the horizon. In approximately 30 minutes after this the illumination quickly increases to about half of the daily maximum value. Therefore actual photoperiod is about 9 hours.

Advantage #3: Ability to adjust illumination and spectrumWhen using dimmable drivers, the light emitted by LEDs can be easily adjusted.

In comparison, conventional fluorescent tubes need to be replaced once every four to six months.it means that they will have to be replaced at least 20 times during the lifetime of a LED fixture

Lifespan of the best LEDs available in the market today (Cree XT-E, LUXEON Rebel ES) is indeed very high, if sufficient heat removal and properly conditioned power are provided.If all the required operation conditions are fulfilled, we will still be getting about 70% of LED's initial radiation power after 40 (150) thousand hours of operation. These figures translate to 10 (33) years of operation of a light fixture, providing 12 hours of operation daily! After this period the LEDs will continue to lose luminance, reaching about 50% of the initial value after 100 (200) thousand hours!

Advantage #2: Extended life cycleAs a solid-state light source, a light emitting diode does not have quickly wearing parts, such as an incandescent filament. When operated at or below rated current, and providing that they do not overheat, high quality LEDs degrade very slowly.

The advantage of using LED are: Advantage #1: Higher efficiency and less heat generationHigher efficiency has two components. First is that LEDs are about twice more efficient than conventional fluorescent tubes or Metal Halide bulbs in converting the electric energy into light. Second is that LEDs only radiate in one direction of the plane and hence are not apt to block their own light.

The intensity of light is also very important for growth and active production of fluorescent chromoproteins. The saturation limit of photosynthesis is about 600-700μmol·photons/m2/s. However, it is not always a good idea to provide as much light in home aquaria, since a coral can become very demanding to its environment parameters under such high levels of illumination. Under less than perfect conditions such high levels of illumination can yield a contrary result: coral bleaching.Concluding from the above, light in the 400-500nm range is most beneficial for marine photosynthetic organisms, and its shortwave portion (400-450nm) is most useful for their bright coloration.

The conclusion of the article is that "the enhancement of coral pigmentation is primarily dependent on the blue component of the spectrum and regulated at the transcriptional level

The strongest fluorescence will be observed in 400-450nm range, particularly because the eye sensitivity in that range is very low. The light in this range is usually called "actinic light. The light in the 400-500nm range also has other importance: it is the most optimal light to promote marine photosynthesis. Therefore this part of the spectrum is of utmost importance for a reef tank

(A) low concentration of chromoproteins, the color of zooxanthellae dominates; (B) green fluorescent proteins; (C) red fluorescent proteins; (D) non-fluorescent chromoproteins.

Fig. 5 shows four specimens of the same species, Acropora millepora, in which different chromoproteins prevail:

Corals can be very variable, and even the same species may contain different chromoproteins (proteins responsible for coloration)Many of these proteins are fluorescent; i.e., they adsorb the light of a certain wavelength and radiate a different wavelength

Three main factors which affect the coloration of the coral most: light spectrum and intensity, the amount of food available in water (although coral polyps receive a significant portion of their energy from the zooxanthellae, they are also able to capture food particles from the water column), and from the purity of the water. This last factor is easiest to control.The second factor, too, can be solved easily since there are a number of quality coral foods readily available on the market. At the same time many aquarists believe that, if there are fish living in a reef aquarium, corals will get sufficient food from small particles which float around from feeding the fish (and fish poo too is consumed by corals).Light is the last important factor required for good health and the coloration of corals

The horizontal axis is the wavelength, in nanometers, and vertical axis is adsorption, in arbitrary units. You can see from the graph that violet and blue colors strongly prevail over red (note that for red spectrum, the 660-680nm range is preferable).Our main conclusion from the above is that violet and blue light are most important for marine photosynthetic organisms.

During hundreds of millions years of evolution marine photosynthetic organisms adapted to best utilize mainly the violet and blue parts of the spectrum, which is more abundant in their environment, and are not very sensitive to the red spectrum

That is all for today. Tmrl we continue to on light adsorption by zooxanthellae.

The light-blue graph corresponds to irradiation on the surface, the blue graph - to 5m depth, and the dark-blue - to 15m depth. Note that with depth, the red part of the spectrum virtually disappears

Fig. 3 show us light's relative spectral distribution at the surface and at the depths of 5m (about 16.4 feet) and 15m (49 feet). Note: 15m is the maximum depth at which we can still find many light-demanding corals in nature. At the depths below 20m, the number of light demanding species sharply decreases.

The horizontal axis is the light wavelength, in nanometers(nm) , and the vertical axis is depth, in meters, at which the intensity of that wavelength is equal to one percent of the intensity at the surface. It is clear from this graph that wavelengths between approximately 370 and 500nm best penetrate into the depth. In other words, violet and blue parts of the spectrum penetrate best into seawater, whereas green light is much worse at that, yellow-orange is even worse, and red light with wavelengths longer than 600nm is only capable of penetrating very shallow waters. This data is very important in designing or providing the light to your reef aquarium

Below is the graph of solar light penetration into marine water, depending on wavelength, compiled by the Institute for Environment and Sustainability of the European Commission [4] (Fig. 2):

Different coral species live on various depths: some live in very shallow waters, whereas deep water corals, such as Bathypates spp., can be found on the depths of up to 8000 meters (about 5 miles). About 20% of all coral species are non photosynthetic; they do not require any light as a food source. Most corals, however, are photosynthetic, and these are the species which are kept most often at home aquaria. We shall try to figure out what kind of light they prefer.

Feature Article: Light in the Reef AquariaBy Dmitry Karpenko, Vahe GanapetyanLight is one of the main life-supporting resources on our planet. Being photosynthetic, many marine invertebrates require light to live. Their symbiotic zooxanthellae need light for photosynthesis to produce sufficient nourishment both for their own use and for the host coral.Perhaps every reef hobbyist is willing to provide the "right" light to his corals - both correct spectrum and sufficient intensity are important. Before we consider how to implement this "right light," we shall first try to understand what kind of light marine organisms get in their natural environment.

You can read up yourself athttp://www.advancedaquarist.com/2012/10/aafeatureor you can read my summarise copy by following this thread for the next couple of weeks