Fish Eheim

January 23rd, 2008 admin Leave a comment Go to comments

Fish Eheim
Why is the coral in my fish tank green?

I have an African Cichlid tank it is approx. 8 feet, by 2 feet by 2 feet, it has been up and running for about 2 months now. At the moment it only has around 11 small cichlids in it and I have an eheim anemone filter and the tank is extremely clean and the Water is clear. However, I have a very course white coral on the bottom that was recommended because it elevates the Ph. level- but some of it is turning green. Now it is not a growth ON the coral, but the coral itself that is turning a dark green- you cannot scrape it off or anything like that. The water quality is still great- Ph is 8.8 , no ammonia, no nitrate, very clear and the fish are healthy and colouring up great. Any ideas about the green coral?
If the algae is in the pores of the coral how do I deal with that? The rest of the tank is very clean and there is no algae anywhere else.

The coral is green because of algae growth. If it doesn't scrape off when you rub the coral, that's because most of the algae is down in the small crevices and holes in the coral structure.

You could get rid of this by removing the coral from the tank and putting it in the sun to dry for a while. After a few days out of the water, all the algae will be dead and most of it will disappear. If you want bright white coral, you can bleach it (your fish probably prefer it dark, though).

I wouldn't do any of this, though. The algae doesn't harm your fish at all, and in some ways it is beneficial. It helps remove ammonia from the water. Many African Rift Lake cichlids, which are what I think you have, naturally graze on algae growing on rocks in their native Habitat. If they can do something similar in your aquarium, they will be happier and healthier. They eat both algae and the tiny animals that live on the algae. All these foods from rock surfaces are called "aufwuchs" by African Cichlid keepers.

The only potential downside to having live algae on your coral is that, by coating the coral, it potentially makes the coral less reactive with your tank water and thus reduces the coral's buffering effect on the water. However, coral has such a large surface area (because it's so porous) that I don't think this will be a problem. You don't seem to be having any pH problems so far.