Hello all. Everything was fine, and pretty much still is. I wanted to start a frag area in my sump, so I got this black egg crate from a lfs- it's initials are BF. Now I know they don't make the rack, and it was a reasonable price- for black egg crate. After just a week or two- this brown fuzzy stuff is growing on the egg crate, and on most of the frag plugs too. This in the only place in my system this stuff exists! I pulled it out about 10 days ago, scrubbed it off everything, and aftger a few days- back it came, worse now than ever. No other changes. Again, it's the only place it exists in my entire system. What is this stuff? And ideas for getting rid of it. Again- only on this one area- big time.