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Avoid these fishes! YES, Avoid these fishes! Here today we will discuss the most popular fish in the trade to be avoided. Given the beautiful color or the fish or perhaps the cheap price, you should always research and prepare for it as the fishes listed might be difficult to keep or difficult to get it fed. One of the most sough after fish ( Achilles Tang ) which belong to Acanthurus family is very susceptible to ich and require good water quality and large swimming space Ich Magnet Tangs are one of the obvious ich magnets, by saying ich magnets means they are easily susceptible to ich. One of the genus to avoid are Acanthurus which consist of Powder Blue, Powder Brown, Powder Black and Archillis tang are the most common fish to be seen in trade and also most susceptible to disease in a Reef Tank. It is not totally impossible to keep this species however you are required to quarantine every single fish that enters your tank from the start and also prepare to dip anything that enters it too because this is to lower the risk of diseases entering your tank. However, it still doesn’t 100% eliminate the chance of this fish getting caught with ich or die. One way to ensure your fish to be healthy and resistant is to feed them well to build up their resistance and ensure fish is fully quarantined before introducing it to your marine tank. Do also take note of the existing tank mate in your system as if it is not properly introduced, they might be aggressive towards each other and being bullied by established fish in the system which might weaken their immune system making them susceptible to develop ich again. Tangs also required amber swimming space and it is only recommended for reefer with 3ft tank and above. Damselfish Affordable, elegant and beautiful as it seems to be, however so note that some of the damsel species are notoriously aggressive fishes to other tank mates, that will attack another tank mate once it is established. If you really like this species you should consider introducing it last (Which maybe seem impossible because we always want to add new stuff), or introduce a bigger size fish after it. Be sure to research on the behaviour of the damselfish that you will be getting to avoid any aggression. Damselfish might do well in a school in the ocean but however, in a small tank, they often chase and bully themself to death as victims of the bullied may find themself hiding and die from starvation. Copperband butterfly Even myself, I love the beautiful white and yellow colours and also the long peck. However, do note that this fish diet is only known to eat copepods and aiptasia. You can train them to eat Mysis shrimp but it will require a lot of patience for that. Impossible to keep? No. But it has really come to how much commitment you can keep this fish with some stroke of luck as well. Once you are able to obtain a healthy specimen, the chance of getting it to feed prepared food will be higher, and you will be rewarded with a beautiful specimen swimming in your tank. Dragonet (Mandarin fish ) Same as a copperband butterfly, their diets in the wild consist only of live copepods and pods that are small enough to enter their mouth. It should only be kept in an established tank with lots of critters for them to hunt in the while. If you keep in a small tank, train them to eat mysis in a small isolation before release or else they will just ignore the food as they are never going to try to nibble on it unless in a confined area. Weird huh. Fortunately, there are captive breed specimen that is ready train to feed prepared food even pellets as well! However, do prepare to pay a little bit more for these captive breed one. Bicolor Dottyback Small yet aggressive. Dottyback is one of the most common fishes in the marine trade that newbies tend to purchase because they look like Royal Gramma from finding nemo. This fish may look gentle and harmless but do not be deceived by its looks, as once settled, they are really really really aggressive in their own space and always tends to bully new tank mates to death. I would totally avoid this fish but then if you really like this fish, do consider introducing it as the last fish without its own kind/body shape with ample swimming space for it. Pygoplites diacanthus – Regal angelfish is consider one of the harder angel fish getting it to feed prepared food in an aquarium environment. Most eat sponge in the wild. Picky eater Angelfish Some angelfish are picky eaters and it could be challenging getting them to eat prepared food in the captive aquarium, as some of their natural diets in the wild usually consist of a wide variety of sponge. Some species not limited to are Regal Angelfish, Multibar Angelfish and Golden Angelfish are the few of the beautiful angelfish that are often reported hard getting them to eat in a captive environment, which often ends up being dead from starvation. I will only recommend to purchase them if they are eating pellet in a LFS or show sign of feeding . PS: Do find out what pellet brand it is eating and get them to mix with what you feeding with. Lastly, other than avoiding the fish, you should also learn about how to pick a healthy fish which I will write on it next time. If you have more fish you wish to bring to attention to avoid, do write on the comment below. Author - @Willy Guccivera Yap

Why should we Dip corals? and how to perform it A colourful SSC Visiting a local Live Fish Shop (LFS) and shopping for corals is one of the best enjoyment in this hobby. However, do you know that if your newly purchased coral is not treated carefully, it could cause a serious effect on your existing healthy corals which is already thriving in your current marine aquarium system ? What is coral dipping ? As up to 90% of the corals in this hobby is either collected from the wild or cultured in the sea, there is a high possibility that the corals come with pest without the exporter or importer knowing it. The term coral pest simply means, invert or creature in the natural environment that hosts and eats coral polyps, coral zooxanthellae for its survival, and if left uncontrolled, it will keep reproducing itself which could cause a serious effect on all your corals in the tank. However, most of the time, it is hard to detect these hitchhikers , as due to their natural defence mechanism, that includes natural camouflage which makes spotting them extremely difficult with our human naked eyes. Photo credit; Leon tan Therefore, treating all new or infested corals with a coral dipping is one of the best remedies for this . Coral dipping simply means treating the coral with a commercially available solution that helps to remove those pests from the corals itself without harming the corals. However, do note that coral dip could be effective against the pest itself, but it can be useless against their eggs. How to perform a coral dip? To prevent any unwanted pests getting into your system and eating up all your existing prized corals, we should treat all newly purchased corals “ unsafe “ unless it has passed the quarantine period or safety period deemed by the hobbyist. Start with preparing two container filled with tank water and applying a moderate amount of coral dip solution in the dipping container and placing the corals into the container. Two container of water for dip and wash Dipping of corals in a prepared dip solution Follow the instruction of the coral dip products that you are using, and after performing the dip, transfer it to a newly prepared tank water ( Without the coral dip solution ) for a short bath before finally returning it to the tank. Some of the possible hitch hiker like this that can be found after the dip If any pest is found, do prepare to perform a second and a third dip a few days later as there might be eggs present that need to be redipped for any pest. Do not dip the same coral repeatedly as it might stress the corals and cause it to die from stress. Provide enough rest period for the coral to heal before performing a repeat coral dip again. Performing coral dip on mushroom corals However, if no sign of pests is present it might not mean that the newly purchased coral is 100% pest-free, as there might be eggs which are not visible to our naked eye or which has not been hatched during the coral dip that we have done. The dip will not be able to remove eggs, and it has to be done only manually. Which is also why It is strongly recommended to place all newly purchased corals into a separated quarantine system which a schedule dip can be performed over a period of up to 14 – 30 days which ensures that the coral entering the system will be 100% pest-free. If there are any eggs which are not hatched, it will hatch during this quarantine period, and the scheduled coral dip will remove them completely. SPS coral turning pale due to FW attack A infected colony that losses its color SPS with flatworm SPS infected with FW eggs So be prepared for every new coral, be it mariculture piece or coral frag big or small, there is every possibility of introducing a bad hitchhiker into your system which could cause a nightmare to you trying to figure out how to remove them later from your tank. A Possible schedule of a coral dipping process for all newly bought corals includes ; Day 1 – Coral dip and inspect visually for any sign of bite mark, pest, eggs on the corals itself or on the base of the rock that it comes with. ( Depending on the condition of the corals itself, if the coral look stress, or injure it is advisable to postpone this to further stress the coral ) Day 7 – A second coral dip to ensure that there is no coral pest observe during the dip Day 11 – Hitchhiker pests like AEFW ( Acro Eating Flatworm ) take about 11 to 14 days to hatch depending on the temperature, thus by the period this third dip is performed, the eggs would have hatched and dropped off from this third dipping. Day 14 – The purpose of this dip is to ensure that all unhatched eggs from the previous treatment will be by then hatched, and removed by the dipping process performed on this day. Day 30 – Finally the last coral dip is almost certain that all coral entering the main display tank is free of any coral pest and safely introduced into the system. A tank full of happy growing corals. Yes, this could be a very tremendous tedious process of dipping and conditioning the corals to be almost 100% sure that all corals entering your system are almost certainly pest free. However, the effort will be worthwhile over the long run, preventing any outbreak in your existing system which could lead to a total loss of your beloved corals or a more tedious way to remove them later. Author - @he

BASIC REEF CHEMISTRY (PART I) This is the first in two articles dealing with the basics of reef chemistry. This will be written as a crash course on what hobbyists need/ ought to know. The article to follow touches on information, which is useful but not necessary to know. SALINITY The salinity of seawater is typically given either in units of parts per thousand (PPT) or specific gravity (SG). The ideal range for salinity in a reef aquarium is usually placed between 33 to 38 PPT, which approximates to 1.024 to 1.028 SG. The middle ground of 35 PPT (or approximately 1.026 SG) is typically recommended and is the accepted “standard”. Refractometer that measure PPT and SG level PPT PPT is a measure of the total weight of salt dissolved in seawater in relation to the total weight of the seawater reference. In the case of 35 PPT, this translates into 35g of salt in 1000g of seawater. However, to evaporate 1000g of seawater each time to determine the salinity of a solution is obviously impractical. Therefore, there are other methods developed to determine the salinity of seawater. Hydrometer that measure SG level SG SG measures the density of the object being measured relative to the density of a reference. For the purposes of the reef hobby, this refers to the density of seawater relative to the density of pure freshwater. Since density is a measure of an object’s mass to its volume, and the volume of an object changes depending on its temperature, it is important to note that the density of seawater changes with temperature too. As a corollary, the SG of a sample of seawater also changes with temperature. For this reason, some devices used to measure salinity state particular temperatures at which samples should be measured at. This is especially important when using a hydrometer to measure the relative density of a sample of seawater. How then does a refractometer measure salinity? As with a hydrometer, a refractometer does not measure salinity directly. Instead, it is an instrument which measures the refractive index of a sample and correlates it to an SG value. It is important to note the following when using a refractometer: Have the sample at 25 degree Celsius, or simply use a refractometer with automatic temperature control (ATC) which compensates for changes in temperature; Read the refractometer through a light source closest to daylight; and Use only a refractometer designed for seawater, not one that is designed for sugar, alcohol or brine. PH pH is the measure of concentration of hydrogen ions (H+) ions in a solution. The more acidic a solution is, the higher the concentration of H+ ions and the lower its value on the pH scale. As can be seen above, pure water registers a pH of 7 on the scale. It is important to pay attention to pH in a reef tank. A low pH is stressful to fish and can inhibit coral calcification. The recommended pH sits between 7.8 to 8.3. nyos test kit CALCIUM The importance of Calcium, Magnesium and alkalinity in seawater cannot be understated. Aside from Sodium and Chlorine (plus Hydrogen and Oxygen which form water itself), the most abundant elements in seawater are Calcium and Magnesium. In seawater, Calcium and Magnesium are dissolved in solution as Ca2+ and Mg2+ ions. The significance of this is a topic for another day. For now, it is sufficient to note that the amount of Magnesium dissolved in seawater has a bearing on the amount of Calcium that can be dissolved. Calcium is needed for coral calcification. Hard corals use Calcium dissolved in seawater, together with carbonates present, as the primary building blocks for their skeletons. It is no surprise that this process is aptly termed “coral calcification”. Without Calcium, hard corals would not exist as they do today. MAGNESIUM Magnesium is the second most abundant cation in seawater. Its presence in seawater enables a higher concentration of Calcium ions than otherwise possible to be dissolved in seawater. Like Calcium, Magnesium is also incorporated by hard corals into their rigid skeleton. ALKALINITY Alkalinity completes the trinity of crucial components in seawater. Alkalinity is not an element. Instead, it describes the buffering capacity of water i.e. its ability to resist changes in pH. In seawater, alkalinity is affected by two main systems. First, the carbonate buffer system. Second, and to a much lesser extent, the borate buffer system. This article focuses solely on carbonate buffers, save to state that while the presence of borate ions contributes to the alkalinity levels measured in seawater, it itself is not used for calcification. Carbonate buffer (CO32-) Seawater naturally contains carbonate ions (CO32-) and these exist in a chemical equilibrium with other ions. What this means is that carbonate ions, as one reactant, and some other ions, as other reactants, are both present at the same time. Whenever a reversible arrow (⇌) is used, think of it as a reaction that can go in both directions of the arrow. When Carbon dioxide is dissolved in water, it partially dissociates in the following manner to exist in equilibrium with Carbonic acid: Equation 1 CO2 + H2O ⇌ H2CO3 Carbonic acid itself can further dissociate to give H+ ions and bicarbonate ions: Equation 2 H2CO3 ⇌ H+ + HCO3– The bicarbonate ion also exists in an equilibrium with carbonate ions: Equation 3 HCO3– ⇌ H+ + CO32- If nothing is done to a solution containing ions in equilibrium, the ions do exactly what they suggest – maintain an equilibrium. However, if either side of any of the arrows above is disturbed, the equilibrium will shift to account for this change. In other words, a “buffer” against the change. For example, if an acid is added: There will be more H+ ions in solution; The bicarbonate-carbonate equilibrium at Equation 3 shifts to the left to account for the H+ introduced and more HCO3– is present; and This process continues for Equations 1 and 2, with more carbonic acid and more Carbon dioxide resulting. What eventually happens is that the concentration of H+ ions when added to a system containing a buffer does not increase the concentration of H+ ions in the total system as much as would have been the case if there were no buffers present. In effect, the system “neutralises” acids added. A titration curve of such a reaction would look roughly in the form of the sketch below. The same reasoning also applies if a base is added, although the Equations above will be pushed towards the right instead. Importance of alkalinity Maintaining the appropriate levels of alkalinity is important for three main reasons: It is a buffer against swings in pH; It is a good gauge for the amount of carbonates in seawater for corals to use for calcification; and It has an effect on the amount of Calcium ions that may be present. This will be explained in the second article to follow. Do look out for Part 2 of the Reef chemistry .. Author - @pcw

Water Test: Is yours working? Salifert Test kit – One of the popular aquarium water testing brand For many avid reef keeper, one of the favourite past time is to conduct water test. Since the fishes and corals we keep come from an environment which is very stable, it is meaningful for us to ensure our little water tank imitate the natural environment as much as possible. One of the common methods for us to get that peace of mind is to carry out various water tests. However, when you get a reading of 1ppm nitrate, or a pH of 8.21, or an alkalinity of 7.50 dkH, how much confidence should we have about the value? In this article, we will briefly look into different types of water test, and appreciate what they can (or cannot) do. Accuracy vs. Precision This is a topic which have been discussed repeatedly. In short, an accurate result is close to the actual value, while a precise result means different tests results are close to each other. Accuracy and Precision (By Pekaje at English Wikipedia – Transferred from en.wikipedia to Commons., GFDL, https://commons.wikimedia.org/w/index.php?curid=1862863) For instance, for an aquarium water with a pH of 8.2, a set of test results is {7.8, 8.6, 8.1, 8.0} can be considered accurate but not precise, since the tests averages to the true value, but the results are not consistent (repeatable). A different set of tests has a result of {8.4, 8.4, 8.4, 8.4, 8.4} for the same water. The second test is precise, but not accurate. It is far from the actual value, but repeatable. A test is meaningful only when it is sufficiently precise and sufficiently accurate for our needs. There is really not need to use a stopwatch to measure the time to braise a chicken stew. Only when we know the test conducted is suitable for our needs, then we can be confident in the result of the test, and then follow up based on the test result. Another character to consider is the resolution of the test. Resolution is the difference between the two adjacent values. Higher resolution allows us to differentiate two close values, but it does not imply accuracy or precision. Finally, there is the limit of detection. This indicates lowest possible level to be able to register a reading on the test. Again, this does not imply accuracy or precision, but if the actual value is at or near the detection limit, the test may be difficult to produce usable results. Water Test Techniques We shall look at different types of test briefly, so that we can understand the pros and cons of each of them. Inductive Coupled Plasma – Atomic Emission Spectroscopy (ICP-AES) Triton ICP-OES, One of the many test providers ICP tests are currently held as the golden standard of water test. Believe it or not, it has a lot of similarities to the good old neon lights. Water samples are filtered and misted into a jet of plasma. This breaks down everything into individual atom. Different atoms in the plasma emit different wavelengths of light. By detecting the wavelength and intensity of light, we can deduce the amount (concentration) of different elements. It’s not hard to accept that ICP-AES process is extremely competent, but are there any caveats? Test protocol: Different test provider may use different protocol for sample preparation. This can affect what goes into the spectrometer. Atomic Level: The test is good at detecting elements such as phosphorus and potassium, but cannot detect ions such as bicarbonate (kH) and Phosphate. If an ICP test provide kH reading, it is done the same way as you, through titration. Detection Limit and Accuracy: Many elements in ICP are of very low concentration in the seawater, often below the detection limit of ICP-OES tests. In addition, the accuracy of the tests may be quite low in certain cases. So is ICP-OES useful? I’m not an ICP user, but I do believe there is value in the ICP testing. Not so much as to tell us that the copper level is 10.00 µg/l, but to high light glaring problems in the reef aquarium. In another word, use it, but know what it can and cannot do. Colorimetric Tests We now take a look at one of the most common test conducted by aquarists, the colorimetric tests. In essence, colorimetric tests make use of formation of colored dye. The intensity of the color can be linked to the concentration of ions to be tested. After mixing the sample and test agent, we just need to compare the color of the liquid to a chart, and find the closest match. Most of the phosphate and nitrate kits belongs to this category. Hanna Phosphorus ULR Colorimeter. Many reefers swear by this. There are some challenges inherent with colorimetric tests. More often than not, the color differences are minute at the lower range of the scale, and generally difficult to discern. Coincidentally, many of our interested parameters falls at this lower end. Another obstacle to quality test is the color perception of individuals, poor color vision can negatively impact the test result. The alternative to “eye power” is the colorimeter. A colorimeter shine a light though the water sample. Some light is absorbed, and the detector picks up the difference. This process eliminates the need for tedious color comparison, however, it also introduce a new set of problems. Bubbles, finger prints, water stain, scratches, all these can reduce the transmitted light into the detector, affecting the result. In addition, if a different cuvette is used for the reference sample, they must be optically matched to ensure accurate results. Titration Tests Titration tests works by slowly adding a standard solution (titrant) into a prepared test sample. The volume of titrant used when the color of the sample changes will tell us the concentration of the sample. With proper technique, titration is a very reliable test method. Most kH, Calcium, Magnesium and Potassium kits are titration based. Salifert Potassium Kit, based on the principle of titration Here are some tips to achieve reliable test results for titration. Prepare the pipette as carefully as possible. It’s normal to have an air gap between the plunger and the top of the liquid. However, it is not okay to have air bubbles in the liquid column. Use one hand to swirl the sample vial, while using the other hand to dispense the titrant. Take care to minimize titrant landing on the wall of the vial It’s sensible to add about 3/4 of the expected volume of titrants quickly. However, the last 1/4 or so must be added drop by drop. Mix the sample well after each drop, and follow the test kit instructions. some tests may show a color change, only to disappear when mixed briefly. The first drop of permanent color change is the end point of titration. That is where the test should end. It’s okay to add one more drop to ensure the color don’t change any further, but do not count the additional drop into your reading. Electrodes Pinpoint pH Monitor, a type of Ion Selective Electrode With the introduction of reef controllers, electrodes become more and more popular. Aquarists have been using temperature probes to control chiller and heater; conductivity probe to measure the salinity of the water; and pH probes to tune their calcium reactors. The discussion of measurement using electrodes is a daunting endeavor. Let’s just look at some points to note for this article. Most electrodes have limited life span. However, for some electrodes, they can be refreshed with a new membrane and filling liquids. Most electrodes need calibration with known standards. This ensure the reading is accurate. The electrodes needs to be routinely checked for calcium deposits, or algal and bacterial growth. Understand that there are inherent inaccuracy in signal processing, Do read up on the technical details if you can find them. Conclusion There are much more to discuss about water test techniques. For instance, to know more about refractometer, you can read up on this article by Leon. In any case, as long as we know the limitations of different tests we conduct, and know that they give us reliable enough results for our need, We can have the confidence that we are on the right path, water wise. Author - @Willy Guccivera Yap

Nutrients on the Reef (I) Sooner or later, aquarists will encounter the topic of reef nutrient when keeping an aquarium. Many aquarists are often concerned about these questions: Is my nitrate and phosphate level ok? Should I feed my corals more? How do I reduce nitrate? or phosphate? All these are fair questions. Eutrophication is often characterized by overgrowth of algae However, if we approach reef nutrients just by looking at the nitrate and phosphate levels from test kits. We are like a blind man touching an elephant. For we only see a small part of a great picture. For this article, N and P refers to inorganic salts containing nitrogen and phosphorus elements. We will discuss about how an aquarist can reduce nutrient level in a reef aquarium, just like how a driver steps on the brakes to slow down a car Fixed vs. Free Nutrient Queen Angelfish (https://upload.wikimedia.org/wikipedia/commons/thumb/f/f3/Holacanthus_ciliaris_10.jpg/1280px-Holacanthus_ciliaris_10.jpg) Let us consider a fully grown queen angelfish (H. Ciliaris). Show size queen angelfish is a foot long fish weighing almost a kilogram. For a fish of this size, it contains large amount of nitrogen and phosphorus in its body. However, when you add this beautiful fish into your aquarium, the nitrate and phosphate does not rocket through the roof. Why? It is because the nutrients are fixed in the tissue of the fish. Therefore these nutrients are not available for other organisms, such as bacteria and algae. Pellets are a staple food for many captive fish Let us look at pellets then. When we toss a handful of pellets in to the aquarium, does the nitrate and phosphate increases? Maybe. When the pellets is freshly added, the nitrogen and phosphorus are “locked” in the pellet ingredients. When a fish eats the pellet, it digest it, and some of the nutrients become part of the fish. These portion of pellets does not increase the free nutrient of the aquarium. The uneaten and indigestible part of the food, however, will breakdown thanks to the bacteria in the water. This will increase the free nutrient in the aquarium. Thus overfeeding (define as feeding more than fish can consume), and feeding low quality food (contain much ingredients, especially terrestrial origin, which can’t be digested by the fish) are the two main reasons of out-of-control nutrition levels. The much feared algae: Bryopsis (By B.navez – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=9364885) Let us last consider algae. A bunch of hair algae contains fixed N and P in its cell. if these algae dies due to medication or water quality. These N and P will be released, and the free nutrients in the water increases. Without intervention, theses free nutrients will likely encourage the growth of some other forms of undesirable algae or bacteria. Test kit and Expectations High nutrient or low nutrient? We often take reference not from the nature, but from the test kit we use. Take for example, nitrate. natural reef water has a nitrate level around 0.25 ppm. Based on this standard, we may consider 1 ppm nitrate as high, while 0.05 ppm nitrate as low. However, reefers generally consider 1 ppm nitrate to be rather low. This is because many popular test kits, such the Salifert nitrate kit, has a lowest reading of 2 ppm in their normal test mode. Things are not much better when it comes to phosphates. Most test kits are not able to measure the level in the natural reef. The worst challenge, however, is that hobby test kits only measures inorganic phosphates. While there are plenty of organic phosphates in the water. For an aquarium with 0 ppm phosphate from Hanna test, it may have significant organic phosphate in the water. These organic phosphates supplies nutrient to cyanobacteria and dinoflagellate alike. When it comes to organic carbon, well, welcome to the jungle. There are few organic carbon test kits in the market. Not to mention the desired level of carbon is, for a lack of better word, undecided. We don’t care so much about organic carbons because we can’t test it. What if this is the key to reef nutrient management? C-N-P and the Redfield Ratio Redfield Ratio It is only reasonable that aquarist talk about nitrates and phosphates when talking about nutrients in a reef aquarium. After all, the only accessible test kits for our hobby is nitrate and phosphate. The inconvenient truth is, if we cannot test certain things, doesn’t mean it’s not there, or it’s unimportant. Alfred C. Redfield In 1934, oceanographer Alfred Redfield went around and sampled the marine phytoplankton and deeper ocean water. When he examined the chemical composition of these samples, he discovered something interesting. The ratio of C-N-P, as well as other elements, are more or less the same. On average, the ratio is 106:16:1 in terms of the number of atoms of C:N:P. Since then, Redfield ratio is one key idea for oceanography studies. In Aquarium Does Redfield ratio applies to our reef aquarium? Yes and no. Unless you aquarium is a bowl of highly concentrated phytoplankton, or a void consist of deep seawater, the Redfield is not directly relevant for the water parameter. In fact, most of our reef aquarium supports far less phytoplankton than natural reef waters. Therefore, fixating on a magic ratio is generally counter-productive. However, Redfield ratio gives us some hint about nutrients. The C:N:P ratio is a fixed value for a given organism. For example, Chaetomorpha has fixed C:N:P ratio. Nitrosomonas has a different fixed C:N:P ratio. Green Hair algae, cyanobacteria, diatoms… each of them has a fixed ratio of C:N:P. Diatoms, which have different ratio of C:N:P to, say, hair algae. (By Damián H. Zanette – Originally uploaded 01:59, 16 July 2008 (UTC) by Dhzanette (talk) to en:Wikipedia (log).(Original text: I created this work entirely by myself.), Public Domain, https://commons.wikimedia.org/w/index.php?curid=7267563) Therefore, if your aquarium relies on these organisms for export, then we need to supplies them with a good balance of C:N:P. For instance, we harvest chaetomorpha to export nutrients. The carbon is supplied when the algae photosynthesizes. In order to grow, chaeto takes up N and P from the water, thus export thing them. If the concentration of N in water is not sufficient to support the growth, the chaeto will not be able to take up any P as well. The lesson from Redfield ratio is simply: organisms exports nutrients in a fixed ratio. If one nutrient is insufficient, they can’t export other nutrients either. Exporting by Biomass Why do we need to care about the nutrient ratio for algae and bacteria? This is because most of the aquarium relies on exporting biomass for nutrient management. Bio-fixation A fish contains a lot of phosphate. However, adding a powder blue tang into an aquarium does not release these phosphates into the water. The phosphates are “fixed” within the fish. It’s not dissolved in the water. The algae cannot make use of these phosphates to grow. Basically, these phosphates does not contribute to the available nutrient in your reef tank. You are looking a a picture of efficient nutrient export (Reef2Reef forum) If we can grow organisms which takes up nutrients in the water column; fix the nutrient in its cells. Then we remove some of these organism from the aquarium. Voilà, the nutrients are exported. The more these organism grows, the more nutrients they remove from the water. In practice, there are many different approaches to achieve this. Bacteria and Skimming Like it or not, bacteria is the most numerous organism in your reef tank. In the most ideal condition, bacteria undergo binary fission. During the process, one bacterium becomes two, two become four. Before you know it, the amount of bacteria can reach unreal proportions. For instance, nitrosomonas, one of the common nitrifying bacteria, has a growth rate of 3.0/day. If your aquarium starts with a single bacteria, theoretically, there will be 205,891,132,094,649 bacteria one month later. This amount of bacteria would weight more than 200 kg. Fortunately for us, such situation is next to impossible in our reef aquarium. There is limited space and nutrient to support exponential growth. In addition, some bacteria dies off, or become prey to other organisms. Nevertheless, this growth of bacteria can significantly deplete the nutrient in the reef, and cause cloudiness at the same time. Since the reef aquarium can only support a limited population of bacteria, nutrient export is inefficient unless the bacteria is constantly removed from the aquarium. Lucky for us, bacteria tends to flock together. This bacteria flocks are easily removed with protein skimming. Skimmers remove bacteria flocks, diatoms and whole lot of stuff from your water Algae as a form of nutrient reduction Growing algae outside the display tank is a natural and effective way for nutrient reduction. Aquarists can grow turf algae within an algae scrubber. Alternatively, they can grow macroalgae in a refugium, or more recently, a reactor. Algae, being slightly more complex than bacteria, grows and propagates much slower. Therefore it takes longer for an algae based export to be up and running at full capacity. Algae make the required organic carbon mainly from photosynthesis. However, different algae contains different proportions of N and P; and these inorganic nutrients must be take up from the free nutrients in the water column. This tiny detail is significant, because it affects the efficiency of an algae scrubber or macroalgae refugium. Algae Turf Scrubber (image from carousell) In an algae scrubber, the aquarist does not purposefully keep a (few) species of algae. Many different algae species compete with each other based on available nutrients and space. When the phosphate is higher, for example, more brown algae will grow. In a way, an algae scrubber is effective across a wide range of water parameters, and it is self-tuning to a certain extend. In a macroalgae refugium, the aquarist has to provide proper nutrients for the chosen species of algae. If a species of algae use up most nitrate in the water, but leave behind a lot of phosphates, then the aquarist needs to intervene to maintain the balance. If an aquarist pulls some algae from refugium, and feed them to the fishes, are they exporting nutrients? Please let me know your thoughts in the comment below. Corals Corals, as well as photosynthetic invertebrate such as tridacna clams, requires N and P to grow. Therefore by growing these desirable organisms, aquarists unknowing remove some of the nutrients from the water column as well. Since growing corals and invertebrates is the main goal of a reefer, this export technique is almost perfect. The problem however, is that the corals and inverts are more advanced than algae and bacteria. Therefore they grow slower, and also demand a more exacting water quality. Managing Nutrient Imbalances The methods listed above exports C-N-P at the same time. What can we do when the nutrients become out of balance? There are two tools in our arsenal: we can add in the limiting nutrients, or we can export the excess. When it comes to addition, carbon dosing is extremely effective to provide the limiting nutrient for these bacteria: organic carbons. Addition of organic carbons directly into reef waters allows faster growth of bacteria, This, coupled with an efficient skimmer, can be very effective to export large amount of N and P. In some aquaria, when N and P becomes imbalanced, the aquarist can dose nitrate or phosphate to make up the difference, and eventually achieving a lower level for both N and P. Selective export method; for N and P gives aquarist fine tuning ability to adjust the level of specific nutrients. Sulfur denitrator removes nitrate from the aquarium without affecting the phosphate level. On the other hand, phosphate media such as GFO and aluminum oxide takes care of phosphates without changing the nitrate level. Conclusion and More I start discussion from the perspective of nutrient removal, because achieving low nutrient level is the goal of many reefer. However, just like you need both accelerator and brake to drive a car, reefers need to know how to increase the nutrition in the water. Remember, the goal of reefing is not to get nutrients as low as possible, but to provide correct and stable level of nutrient based on how your aquarium is run. In part II of this article, I would discuss the flip side of the coin. we will look at how we can increase nutrients in the reef in a controlled way. Meanwhile, keep the nutrients low where you want them, and carry on reefing. Author - @JiaEn

Comparison: Natural Sea Water VS Salt Mix As seen in many online discussion portals, there’s a lot of debate about the comparison against Natural Saltwater (NSW) vs Salt Mix (SM) debating which is a better option. Today I’ll will try to share with you and break down the pros and cons between NSW and SM for you to decide which is more suited for your tank and why is that so. Natural Sea Water Seawater pack into 10L bag from Ah Beng Aquarium Natural Sea Water (NSW) as the name applies, is collected naturally from the sea. usually, it involved a special vehicle that collected the seawater from one of the remote places of our shore and transported to the Live fish shop. As the natural seawater is dirty and could contain dirt, some form of preparation and filtration is required before it is put up for sales. The Live Fish Shop (LFS) will usually filter the raw seawater before selling it to you to make sure that the water is clean and to prevent unwanted organisms that might come along. MOST LFS will usally do a simple form of treatment and filtration themself which usually involves running the seawater through small micron filter sock , ozone and UV to sterlise the water before use. Now let us break down to the Pros and Cons for easier understanding. Pros Natural Seawater (NSW) is “cycled” and ready to be used completely, as it usually contains live beneficial bacteria from the sea. However, if you’re setting up a new tank, the live bacteria that contain in the natural seawater will greatly help speed up the cycling time of your new tank. You’re not required to put anti-chlorine for NSW (Never trust tap water, you never know what it contains) or use RO water to mix because it is already ready to be used right away. It is cheaper to purchase as compared to buying salt mix. All you need is to purchase the NSW and use it. It is simple and easy to use- No messy mixing of salt water or RODI filter required to prepare your water for saltmix. Cons If you are intending to store your NSW for future way, It required circulation else the live bacteria might die and this method could take up space as well to store it before use. The parameter of NSW is not stable, as the salinity will vary between season and weather. Especially when collecting the seawater after a heavy rain, the salinity will definitely decrease. Our local Natural seawater range from 1.019 to 1.023, so topping up of salt is necessary to bring it up to the ideal level.. Naturally, a lower salinity could also mean lower parameters like low calcium, KH , mg etc… Which required topping up of these elements as well for a reef tank. Although there might be some form of filtration carry out, there’s might still be a chance of parasite being introduce into the system if you are using NSW as it is not 100% filtered due to the large volume they handle. Logistic wise, delivering NSW is a nightmare as just to imagine having to carry 10 bags of NSW back home for a major water change, so, all in all, it might not be cheap after all. If you’re keeping a ratio of corals that depleting your elements faster than you replenish the elements, using seawater that has a lower parameter might result in your corals depriving the corals of elements example (CA, MG, KH). Which means you need to dose more of these elements, which add more cost to it as well. unlike using a salt mix , If you are using NSW, you will not be able to know the water parameter of your batch of NSW that you are using, unless you tested it, and bare in mind each batch of NSW that you use the parameter might be different. Various brand of saltmix ( ref; bulkreefsupply ) Now let’s talk about salt mix. Video on how salt mix are produced. The term salt mix simply means using aquarium salt to mix with your freshwater to produce synthetic saltwater that is suitable for both marine fish and corals. (Most of the time, we would recommend using a RODI filter to produce pure water which is free from any harmful impurities or substances which is often measured by TDS level. This would avoid adding any unknown source of the chemical into the salt mix that you are preapring. A typical 5 stage RO/DI water filter *Total dissolved solids (TDS) is the term used to describe the inorganic salts and small amounts of organic matter present in solution in water. There are many various selling brands of salt mix available in the market, however, the prices of the salt vary from the country of origin, brands, parameters and weight of it. Here’s the Procs and Cons of using Salt mix. Pros Control level of trace elements that you know what you are adding into your tank. No unwanted parasite Easier to store as you only need to take out and mix when needed. No expiry date – Generally salt mix can be store for a long period of time without getting bad. Might be cheaper comparing to NSW to produce more saltwater vs weight. Cons Need to mix and wait for the salt mix to be fully dissolved before use. BE PATIENT Need to dose bacteria especially when using it on a newly setup tank. However, some new brand of saltmix come with bacteria in it as well. Relatively expensive for small water volume change. (Unless you are buying in bulk) Require you to invest in a RO/DI water filter unit for your saltmix. To learn how to use salt mix with RO water, check the video below! That is it for today’s articles. Both have its advantage and disadvantage but it all depends on what kind of system do you want to run in. If you are interested to know any topic feel free to let me know! If you want a clean and stable parameter every time you do a water change, Salt Mix could be the best option for you! To understand more about reef chemistry and how it affects our reef tank, you may read more about this article here. Conclusion If you want to establish your new tank fast or if you want to do a major water change without requiring the time to stabile the parameter, then you can consider using NSW since it comes with bacteria. However, if you are doing a water change to replenish your existing tank water parameter or if you are concern about the safety of the water then using a salt mix might be a safer option to go for. Author - @Willy Guccivera Yap