JiaEn

Variety is (Not) the Spice of Life One of the ever green reefing dogma is "Feed a varied diet". If a fish is sick or recovering, if an aquarist looking for better fish growth, or more vibrant color, the advise is almost always "feed a varied diet". This idea has been around since the very beginning of reefing, and is still held as the golden truth by many. But is it? At the Beginning At the infancy of reefing, there is really not much choices for fish food. Banana, cooked spinach, discus pellets, these are the food which are given to the marine fishes. These food does not have the correct nutrient profile for our marine inhabitants. Aquarist soon realised. If they were to feed only spinach to tangs, they don't do all that well; if they feed only tubifex worms, the fish also don't do that well. However, if they mix and match different foods (at some arbitrary proportion), the fish fare much better. The idea that varied diet is important stem from the limitation that there is no good food for marine fishes. The Advancements Thank goodness those days are behind us. We the modern reefers a blessed with much better understanding, as well as amazing products in fish nutrition. In many prepared foods, ingredients of marine origin takes centre stage. Cold extrusion process reduce nutritional damage to whole marine organisms. (Micro)encapsulation ensure precious lipids such HUFA are not degraded rapidly. Freeze-drying, chilled gut-loaded planktons, we are now equipped with many options for good fish nutrition. Therefore it's possible to supply generally complete nutrition to a fish through a single well designed fish food. Then will it be better to mix pellets? It must be better to have even more choices, right? Anyway, I need to use up the bottle of xxx food. So it's better to mix them? This is where I have a different take. In my opinion, mixing food reduces, rather than supplement the nutrition profile. Hear me out. Junk Food for Better Nutrition? Imagine making a commitment to have a healthy diet. After planning out all the meals, you see the packets of junk food on the counter top. "Let's add in all these junk food into the diet plan, maybe I can replace some of the healthy option with potato chips. Afterall, they would help to make the nutrition complete. " The absurdity of this is, i hope, obvious. In the same vein, by substituting a high quality food with a lower quality one for the sake of variety, is an exercise in futility. Do Your Fishes Mind? I highly doubt it. Fishes evolved their physiology and behavior to take advantage of the limited food source in their environment. Some fishes are so specialized such that they eat a single type of food in the wild. I guess when we mix different color of pellets together to feed the fish, it feels more "right" to us. To the fishes? I don't think they care. So think again when u want to offer your fishes "a variety of food"

I find that if I add more organic nutrients in the aquarium, the growth of coraline will be quite reduced. I use FM organics and FM amino Basically the tank is at the state where the organics are too much for coraline to grow, but too little for cyano and dino to grow

The Tragedy of 99% My roseband wrasse died due to my negligence. After routine cleaning of the sand bed, I place the jump guard back as usual. This time round, I didn't put it back properly, and there is a 1/2 inch gap between the panels. Well. The 1/2 inch thick fish through sheer will and coincidence, jump through the 1/2 inch gap, trapped on top of the jump guard, and died. 99% of my tank was covered. 1% killed the fish. The Lesson of Inevitability We always hope the aquarium is accident free. However, hope is after all, hope. Without warning, a sea cucumber may decide to sleep at the over flow and block it; an anemone may decide to put it's foot through a wave maker. Or maybe a turbo snail may decide to knock over the most expensive frag, so that it drop into the arms of a torch coral. No, it doesn't happen often. It probably doesn't happen for many years. But remember, all it takes is once, and the damage is permenant. Given the confine of the aquarium, it's not the question of if, but a question of when, the misfortune will happen. So, as reefers, we need to be vigilant. Don't let the 1% carelessness undo the diligence of 99% *looks like I have to get a roseband wrasse again.

Yes, urchin can help a bit, but rather insufficient. I take the approach of managing coralline like any other algae - deny them favorable conditions for growth.

Welcome back to reefing! Modern dry rocks such as macro rock are very clean. So there is much less worry on absorbed phosphate. This is true. However, once you start to stock up the aquarium with corals, these can come along. It does take quite a bit longer for the tank to mature, but it will happen eventually. About the coralline algae, I view them as a nuisance species. They consume plenty of elements, and takes up surface which should be encrusted by corals. I try my best to prevent them from growing.

Reporting back some finding. I have placed this colony of sun coral in my sump, right after mechanical filtration. It's in the same chamber as my zeovit reactor. My sump is unlit. Most of the polyps are out, most of the time. So most likely they do feed on bacteria plankton.

This I'm doubtful. The problem of NP imbalance imo is due to the export side issue: algae use more nitrates. Dry food also have many low phosphate options if that's what is needed. Yes. Other than the phosphate issue, I find algae based system competes too heavily with my corals. So I switched to a bacteria/diatom system. Hybrid zeolite. So far for the nitrate and phosphate management is fairly consistent and hassle free.

Thanks! Got it. Nitrate-phosphate imbalance is rather undesirable, and GFO use for bigger tanks can get rather expensive. Our experience with algae based filtration seem alike.

Hey. Sorry to dig up old text . Would like to chime in that I used to run algae based filtration, and inevitably will run into phosphate problems which requires GFO to address. Do you still use GFO?

The Eyes Deceive Continue with the discourse on aquarium lights. There are many nuanced issues which we should take note. Among all the challenges for us to "see" the difference in the aquarium light, the biggest obstacle is our own eyes. A quick recap of PAR, the largest peak of the spectrum is in the sub 500nm region. Unfortunately, our eyes are not zooxanthellae. Instead of adapted to the underwater environment, where the most avaible spectrum is blue, we are terrestrial and is more able to see longer wavelength lights. Therefore even when an aquarium have extremely potent blue spectrum, it can still appear not so "bright". Same happens during solar eclipses, although the sun looks dim, the low wavelength spectrums are actually very intense. What I'm trying to say is, it's unreliable to judge the PAR value of the lights based on visual inspection. The Brain Decieves The lights recieved by the eyes activate the neurons and transmit the signal to the brain. The brain processes the signals and piece together the image. The human visual system is very impressive. Not only does it have an impressive 24 stops of dynamic range (a top tier DSLR have about 16), and it can carry out impressive white balancing on the fly. This is why when we look at our aquarium, we can see both the acropora at the brightest crest, as well as the peppermint shrimp hiding in the darkest corner. This is also why, corals looks pleasing enough without the use of a yellow filter. Our brain does the filtering for us. Thus the difference between what we see and the heavily filtered photos, is just a matter of preference. Camera or eyes, there is always filtering involved. For me though, since I enjoy my aquarium with my eyes, I prefer to judge the color of coral based on what I see. The Profile? When we turn the blue channels to 100% and white channel to 25%, it doesn't automatically mean that the blue spectrum is 4 times more than the rest. Depending on the light set, the number of the LEDs in a channel can be different. For instance, Radion XR15 G5 has only 12 cool white LED to go along with 24 blue and royal blue lights. It's easy to see that even when all the channels are set to 100%, the overall spectrum is still going to be very blue. It's interesting to note that these lights are capable to produce neutral daylight looking aquarium. It's also important to note, that percentage profile for channels between different brand or model is not a useful comparison.

An image interlude before more walls of text.

To (not) Imitate the Sun Let's start by putting away the delusion that aquarium lighting is meant to imitate the sun. Sunlight striking the surface of the sea is intense, continous and almost unidirectional. Firstly, the intensity of the solar radiation is very high. The average solar irradiation on earth surface is 1380 W/m^2. This means for a 3ft tank, it needs to recieve 566 W of irradiation. If we assume the LED lights are the most efficient ones, (50% efficiency), we need 1332 W worth of light set to power the 3ft tank. Crazy, right? Secondly, the solae irradiation is a continuous spectrum, without missing or diminished wavelengths. In the era of LED lights, we are faced with the possibility of missing spectrum. Although the overall color of the light may look similar, if the spectrum to excite some florescent proteins are weak, or missing, the expression of those colors will be weak or completely absent. Lastly. The solar radiation strikes the surface of the Earth more or less parallelly. This impacts the light profile in a really big way. Because the light is largely parallel, it almost doesn't spread further as we get further from the surface. In contrast, the aquarium lights are generally close to the surface. As the result, the radiation rapidly spreads out and it's intensity rapidly declines. This is the reason why, while some corals thrives over a depth range of more than 20 meters in the wild, they cannot adapt to the 2 ft of aquarium depth. Therefore, although it's a noble goal to bring sun to our artificial reef, it's impractical, and ill-advised.

Indeed fleece style filtration is not condusive for planktons. But perhaps good generation and less aggressive mechanical filtration may spare enough?

Yeah. Bracing take away quite a lot of light. It's interesting to shape the growth pattern by adjusting topological light profile

Do I see a hot spot of light where the Bali slimer grows sideways rather than up? Right hand side half way up.

Fluctuations One of the tenet of reefing is that the parameters need to be stable. How much fluctuation is acceptable? Is it the best for my reef if parameters don't fluctuate at all? With the advent of modern reef computer and monitors, more and more reefers see their tank parameters in ever finer resolutions. Inevitably, with the ability to measure, comes the desire to control. Do we need to care if the pH fluctuates by 0.5? Or should we be concerned when kh raises by 1dkh? Is there any benefit to keep the temperature within a 0.5℃ window? Just like everything in reefing, there isn't a one-size-fits-all answer. But let me offer some perspectives Homeostasis : Foundation of Life Living things have the ability to respond to the environment, and tries to maintain stable internal conditions. Take, for example, a typical Singaporean born and raised in the tropics. The envrioment around him is fairly warm and humid. In a warm afternoon of 34℃, he needs to take action to keep his body from overheating: his skin capillaries dilates, allowing more bloods to carry the heat to the surface. He also starts to sweat, cooling down his body through evaporation. When he travels to Norway on holiday, where the air is freezing cold, he has to take actions to keep himself warm. Blood circulation is reduced to the skin and limbs, reducing heat loss. He even shivers every now and then, generating more heat as the muscle spasms. There are a few lessons here for us: 1. Living things can adapt to a changing external conditions 2. There is a window of adaptable condition, out of which, survival is unlikely. 3. The more adverse the environment, the more energy is spent to maintain homeostasis. What about Fishes and Corals? We need to understand, the internal environment of a fish or coral is very different from the water in which they reside. Just like your internal organs have very different properties to the air around you. The reef water have very low phosphates, but corals will use different methods to concentrate phosphates in it's tissue. Reef building corals manipulates pH at some locations, and facilitates the building of calcium carbonate skeleton. There are many complex actions done by the corals and fish. All these costs energy. Energy Cost of Adaptation Therefore it's not hard to imagine, if a coral with less energy reserve will have a more difficult time to cope with adverse environment conditions. It's also not hard to accept, that a coral or fish living in harsh environment, or struggle to adjust itself to cope with fluctuations, may use up more energy than it gains. This energy deficit is really what causes the corals to eventually perish. As the energy reserve dwindles, the organism have less resources to maintain homeostasis, and eventually, dies. Thats why often, corals don't die immediately following a mishap, instead, they waste away a few days or weeks down the road. That's why, when some unfortunate accident happens, some corals survive, and some does not. So what is the acceptable fluctuation? One that is well within the limit of adaptation of your livestocks.

I have been thinking about the feeding habit of these NPS. They have colonial polyps which require individual feeding. I am quite doubtful that they can all have a good share of bigger pieces of food in the wild. The density of larger sized planktons is just not that high. Thus I suspect they actually prey on smaller nanoplanktons I did some quick search on papers regarding the gut content of Tubastrea sp. , it seems that 70%+ of the content is in fact nanoflagellates. If so, would an aquarium with robust nanoplakton population be able to sustain these animals without additional feeding?

Thank you for your encouragement

Florescent Proteins While zoox supports life functions of coral, and gives it the much dispised brown color, the florescent proteins (FP) are the reason why we try so hard to keep corals in our aquarium. FP are complex molecules which require a lot of resources to produce. If coral pays hefty price for these proteins, they don't do it just to please our eyes. In fact, FP are essential for coral to survive. FP and Zoox One important reason for the existance of FP is that zoox are very selective when it comes to the type of light it can use. As it turns out, zoox can only make use of light of certain wavelength (can think of it as color). The wavelengths of light useful for photosynthesis is called PAR. PAR spectrum (https://images.app.goo.gl/v49E7u1a1N1ZADo87 Wikipedia ) The light energy unabsorbed by zoox are wasted, or worse, can cause photo damage to the coral tissue. Fortunately, coral evolved a mechanism to deal with this two challenges: Florescent Proteins. Spectrum Shifting and Light In a nut shell, FP absorbs a light of a certain wavelength (this is called excitation), then release the light at a longer wavelength (called emission). This achieve two goals: 1. When the wavelength of the light is increased, the energy of the photon is lowered. So even if the light is unused by the zoox, it will not cause too much harm to the coral 2. When the re-emitted light is at the correct wavelength to be used by zoox, the light energy is not wasted, and coral will gain more food in return. Therefore, it is not difficult to infer the factors which drives the coral to produce FP, and achieve amazing colours. The light must be intense enough such that corals require protection from photo damage. The spectrum of the light needs to be predominantly of lower wavelength (higher Kelvin rating) so that they allow the FB to shift the wavelength up. Hence we arrive at standard reef lighting formula : bright, blue dominant light. [Interlude: for modern lightsets, even for day light appearance, the spectrum is still very blue. Our eyes are not sensitive to blue lights. Therefore even with the elevated blue channels, the aquarium can still have the daylight appearance] The advent of LEDs brings about a second challenge. Unlike MH or T5, the spectrum of LED light sets are the combination of each diodes. These diodes have very narrow emission spectra. Therefore, although a led light might follow a certain spectrum profile, it is possible for some wavelengths to be very weak, or even nonexistent. If the excitation wavelength for a particular FP is absent, then such florescece will not be observed. I believe, when it comes to coral fluorescence, the most important factor is the light. Of course, the coral must be healthy. Building Florescent Proteins Many reefers have read about the trace elements. Iron for green, potassium for red, iodine for blue etc etc. Like wise, reefing products reinforce this idea and have various "color" additives based on trace elements. With all these information, it's fair to assume that these trace elements are in the FPs, right? Turns out this is very far from the truth. The animation below shows a typical green fluorescent protein (GFP). (GFP Movie showing entire structure and zoom in to fluorescent chromophore. (Erin, https://en.m.wikipedia.org/wiki/Green_fluorescent_protein#/media/File%3AGFP_Fluorescent_Protein_Movie.gif) The exterior of the protein is a structure called beta-barrel (green). This structure shields the central chromatophore (yellow) from the surrounding environment. The chromatophore is responsible for the florescence, while the beta-barrel minimizes effect of interference from surrounding environment. Where are the trace elements? Is there an iron atom/ion in the chromatophore? Turns out there is none. There is no heavy metals of any kind in the FPs. Even more surprising, is the fact that many of those "trace elements" can have a chemical quenching effect, dramatically reduce the florescece of the FPs. What is needed for FP building, is amino acids, not trace elements. The Paradox Therefore, the paradox. On one hand trace additives are not a part of FP. On the other hand, adding trace additive improve the color of the corals. Why? I'm puzzled. Could any one suggest a possible theory?

Accidentally clicked post before completing ...Without the zoox to absorb the light, the coral produce florescent proteins to absorb powerful solar radiation, and reduce light stress. This is the reason why corals have fancy colored growth tips. The same thing happens when coral bleaches, as the coral tissues loses zoox, they become vulnerable to photo damage. If the coral have sufficient reserves, they produce florescent proteins to mitigate the damage. That's why bleached corals can look surreal for a while, just before they succumb. Excessive zoox, on the other hand, presents another challenge. During photosynthesis, the zoox produces oxygen. At higher concentrations, this can cause oxidative damage to the coral tissues. To a certain extent, coral copes with this by expelling some zoox. They can only do so much though. If the zoox population gets too high, the coral will fail eventually.

Zooxanthellae When it comes to coral color, aquarists often focus on two factors: zooxanthellae and florescent proteins. The zooxanthellae (zoox) which is a symbiotic organism living within the corals (zoo-: animal, xanthe: yellow). Like the name suggest, zoox are yellow in color. They live within the tissue of coral, grow and multiple based on the availble inorganic nutrients. Coral derives nutrients from zoox, and in turn provide refuge and inorganic nutrients to support their photosynthesis. Since zoox is yellow, its concentration will directly contribute to the golden/yellow color of the coral. When the zoox density increases due to high nutrient availability, the coral tissue will take on the characteristic brown color. Therefore, the browned coral is not necessarily unhealthy. Another important role of zoox is to absorbe lights shining on the coral, thus reducing the light-induced stress experienced by corals. Corals evolved to maximize utilization of lights, such that their tissue is largely transparent, and their skeleton is pristine white. While it allow more lights to be available for the zoox, it also provide little defence to photo damage. This is the reason why bleached coral often decline rapidly. One part of the coral, which contains very little zoox, is the growth tip of the corals. The tips are generally pale and fragile. Without the zoox to absorb the light

Coral Fluorescence Coral fluorescence is one of the topic which puzzles me greatly. The florescent proteins and zooxanthellae density are all well studied. But what we do in the hobby, or rather, what works in our hobby, is not well explained by the science behind coral fluorescence. I will attempt to compare the science with practice, then perhaps we can see if there is any missing pieces of the puzzle. Coral Fluorescence in Hobby When it comes to reef keeping hobby, the ways to achieve good fluorescence for corals, especially SPS corals, are well established. We start with water containing very low level of nitrate and phosphates. Then we attempt to keep the pH high, and the "big 3" elements stable. Next, we use intense light and vigorous flow. Finally, we feed the coral, with planktonic mix, amino acids, and dose trace elements to achieve shining color. For most of us, this works well. Some of these factors are easy to understand. Having stable water parameter close to the reef environment definitely reduce stress for the corals. Giving suitable food in the form of planktons and amino acids ensure corals have sufficient nutrients. The intense light encourage the formation of florescent proteins to protect the coral. All these are well and good. The problem is with the trace elements. On one hand, dosing trace elements (such as FM colors, Redsea ABCD) leads to improvements in coral color for me (and many others); on the other hand, the idea that trace elements is needed by the corals to form florescent proteins is highly debatable. In the next post I will list down some facts, maybe one day we can truely know the mechanism of coral fluorescence.

It's meant to hang outside the tank. But yeah. It's not cheap, but it's very efficient.

Deltec MCE 300 is extremely effective, but a bit ugly

So far it works for me. I would say the nutrient level in the aquarium is good and sustainable. A bag of zeolite will not work nearly as well, because it's the periodic shaking and tumbling which cause the bacteria flocks to be released into the water . It will. but of course, there is a limit as to how much imbalance it can correct. One good thing about ats is that, you don't have to pick out the "correct" algae. The natural competition will take care of it for you.