I have a 47 gallon tank with 4 neon rainbows, 2 Irian rainbows, 3 platys, 3 serpae tetras, 2 lemon tetras, 3 veil rams and 2 gold veil rams. My levels are fine, as I check regularly. I have fake plants and rocks which have a brown algae (diatoms?) all over them. I scrape them off at every water change but it seems to keep coming back. I do a 25% water change weekly. I don't overfeed the fish. I think I used to because I've had my tank for 7 months and in total I lost 17 (that I can think of) fish. When I spoke with the LFS they said I was doing everything right, so the only thing I might have been doing was overfeeding the fish. Hopefully I've solved that problem, but I don't know what to do about this brown algae. Could anyone help me? What about a silicate absorbing resin in the filter? I read that on the net. Thanks and sorry about such a long question.