Quote:
Originally Posted by gregzz4
Care to explain how this happens ?
I understand corals can excrete their zoox when under stress, but how do they end up with too much ?
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Essentially too much food. Either in the form of nutrients or too much light, or more likely a combo of both. That, coupled with temp can cause a "bloom" of zoox to grow. Kinda like any other algae in a tank, just inside the coral tissue.
Nutrients are made available through too much feeding, lack of dilution, excessive spots for binding it (detritus within the rock, deep stagnating sand, etc). Nutrients then are hard to measure as they're aren't freely available in the water column, but leach from the various sources to feed the zoox. Too long of a light cycle and higher temps can then amplify their uptake and growth.
I've always found that the best way to tell you have too much zoox is the amount of fluorescing the corals give off under actinics. You'll notice a lot of glowing green from the browner corals, which is something that typically a fully blue piece of SPS won't give off. In my tank for example, the only corals that "glow" under the actinics are the ones that are naturally green. Not an absolute rule, but a pattern I've observed over the years.
To keep the colors I have now, I've minimized the rock in the tank to promote detritus removal, I keep a very shallow sand bed, temps below 80 (but above 76 to promote growth), large and frequent water changes and a nutrient export system (zeovit). I also keep my lights on full for no more than 7 hours.
Unfortunately there isn't usually a single thing that you can change, but more of a synergistic combo of all these things to bring out the colors.