+ How to verify that your sand filter is working.

+ Verify that your filter is working . . . and then do NOT backwash until it's 'full'. If your pressure gauge is working, then you should backwash when there is a 5 - 10 psi INCREASE in pressure from clean to dirty.

+ If there are piles of 'stuff' on the bottom, and you can vacuum that to waste, do so.

+ Foamy water often means . . . you have added pool store goop, which can actually SLOW the process. Clarifier + some stain control agents can be an especially bad combo. Likewise OVERDOSING with clarifiers or 'floc' agents, or COMBINING them can create a chemical mess that is very slow to clear up. Have you added chemicals besides the basics?