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what is this brown stuff in my salt water tank?

Posted by Ezzy1986 NSW Aust (My Page) on
Sun, Oct 9, 05 at 4:14

I came home after two days (and a friend looking after my fish) to find brown stuff on my live rock and on the gravel/substrate.

It is only a new tank, live rock was in there for about 10 days before I added fish. I added the fish and a small coral 4 days ago (2 clowns and a yellow goby) and they were fine for 2 days, i fed them on friday, frozen mysis shrimp. I just returned, Sunday, to find brown 'stuff' on my live rock and in the sand....

Is this normal?
Is this fish waste? or algae?? or something?

Follow-Up Postings:

RE: what is this brown stuff in my salt water tank?

Sounds Like Diatoms. Is it a brown flakey sludge easilly stirred up? Diatoms is very common in a new aquarium both salt and freshwater. It is not nice to look at for sure but shouldn't do any harm, exception If it is a very heavy coating. On live rock it could block high light requirments as well as the coral. It should easily "wash" away. The cause is silicate leaching into the water from your new tank, any plastic or glass equiptment (silicone caulk, heaters filters pumps etc.) Usually when the silicate all leaches out (a few weeks to 6 months, varies with water chemistry and tap water) it will disappear. Silicate is the food source so when its gone it starves. Check nitrate levels also. Do a search on the web for brown algae or diatoms for a more detailed explanation and cure. has some good ones, as well as alot of info for saltwater and fresh water aquariums also

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