Hello, wanted to see if anyone can help identify what is all over the bottom of my pool constantly for the past 2 seasons. Looks like brown dirt, but puffs into a cloud when I brush it. I can vacuum to waste and it will be there a few days later. This is in an above ground pool, I thought it was my cheap filter last season, but now I have a Hayward 21" sand filter/pump and I still get this stuff. My water is clear. My levels appear to be normal, chlorine is 4, PH is 7.4, alk is 100, CYA is 35-40. This is a 24' AG pool, 52" high. Anyone help identify based on pictures?? Thanks!!