I feed with Sallys brine shrimp and truth be told I tend to overfeed a little bit. But it still all gets cleaned up in 2 - 3 minutes. Ive seen this algae growing on the surface of peoples sumps and fuges and was always told it was a type of coraline algae. ?????? No clue. Thanks for eveyones interest hopefully well fig it out. Until then Im gonna keep doin water changes and vacuumin in out.