I also have the same problem. I opened my pool the last week in April, it was swampy green but a couple of doses of shock fixed that. I am told by the pool store that my chemistry is good. I just changed the sand, have used clarifier, and have added floc. Nothing is working. Still cloudy. Can barely see the bottom in the shallow end. Have been running the filter 24/7.
The pressure does not seem to be going up enough to backwash. I've also tried Fiber Clear, backwashed after that, but it hasn't gone up enough to backwash again. I'm getting frustrated. The pump and filter system could be about 25 years old. Could it be time for a pump?