Here is what a few others had to say about it.
Broomer5:
Pretty sure the brown stuff are diatoms, usually refered to as "brown algae". Most always get them after setting up a new tank, natural part of the process. Some tap water may contain with silicates which I understand are the main culprits, causing the diatoms to flourish. Mine came after about 3-4 weeks at end of cycle, and have decreased over last couple months. Got a little green now on substrate, but the brown crap still has to be removed from the glass now and then. Phosphates/Nitrates + a lot of Light = large amounts of most any algae problem. If nitrates are high, do water changes a little more often. If phosphates are high, figure out why and try one of the phosphate removers on the market.
Mr. Salty:
Sounds like the stuff we all get in a new tank. It does clear itself up,but I would suggest using Coral-Vite. It has done wonders in my 125.
My lfs guy told me to try it for algae. It says on the lable it does not promote undesirable algae groth. I know that doesnt say it kills it. But it dissapeared 2or3 days after I started using it. Coincidence? Maybe,But I think it had something to do with it. I had it (brown algae) bad.........
Both these guys are sharks. On my first tank, it cleared up after a while. You can also search on diatom, diatoms, or diatom bloom.
