I can't figure out what keep reappearing on the bottom of my pool. I think it is algea, brownish in color. The puzzling thing is my water is otherwise clear. The FC level runs from 3-5 depending on how recently I have added 12% bleach. PH is at 7.8 AK is at 11 and CYA is at 4.5
I vacuum and it is back the next day albeit slightly.
Suggestions on how to treat and what in fact I have?