My pool was a green swamp when I opened it this year. The cover came off this winter and there was a lot of pine needles and pine cones at the bottom of the pool. I hooked everything up, brought up the CYA to 30 and lowered the PH to 7.2 and then started the shock process. I've also vacuumed and scrubbed the pool floor and walls endlessly. Pine cones are out of the pool. There are still some pine needles in it, but most are out. The pool has gone from a deep green to greyish blue, but we still can't see more than about 2 feet down from the top of the pool. The pool floor is not visible. We've been shocking for 3 weeks and the filter has been running 24/7 for 3 weeks.
At first I thought I had a very tough to beat algae. But now FC levels are holding without a problem and there isn't any improvement in the clarity of the pool water. I've been able to maintain the pool at shock levels for nearly a week without much work (just adding a normal amount of chlorine at night).
I am starting to think I have a filter problem, but I have no idea where to start. The pool is an AGP, less than 3 years old (this is the third season). Filter is a Starbright SF40 sand filter powered by a 2.0hp pump. There is plenty of pressure coming out of the return. I think my pressure gauge is broke as it says zero, but there is a lot of pressure. Should I change the sand? I can't see any leaks in the filter.
Current #s are:
CYA - 30
PH - 7.2
FC - 15
CC - .5
Any help/advice is greatly appreciated.