"BEst guess" question

[aylad]

I'll let the equiment guys chime in here, but I'm thinking your pump may be overdriving your filter, pushing stuff back through to your pool. The DE should help diagnose the problem, but I'm thnking it's just not filtering properly.

[Watermom]

I agree with Jan on all points. Your pump is awfully big with a small filter for this size pool. Adding a pool store goop --- clarifier --often makes problems worse. All the granular chlorine, if it was cal-hypo, could have driven your CH too high and you need POPP!