I did some experimenting today. I hauled about 10, 5 gallon buckets to work with me. I work with fish. I filled 3 five gallon aquariums with my water, and hooked up a mini sand, DE, and cartridge filter. After about 6 hours, the DE had started to clear the water; the sand and cartridge will probably still be the same a month from now!. I tried a few different polymer pool flocs. I used one beaker with nothing added as a control, none of them did a thing. I had cultured for algae last week (just in case I hadn't shocked it into oblivion)...no algae in the pool water (or there wasn't last Wednesday, and I have maintained same cl level). I don't know if any of this will help. Is there a chance that an alum based floc would work?? I couldn't get my hands on any today.