My pool has been very clear since I switched from Baquacil to Chlorine a couple of weeks ago, until about 3 days ago. All at once my pool got cloudy. My FL, CC, CYA, and PH levels are good. Even though my pressure was only 6, I back washed anyway. On the rinse cycle not the backwash a lot of sand poured out. I do not have sand coming out into the pool while it is on filter. Is my spider gasket in the multi-port valve bad, or is there something else going on? Thanks