16x32x52 above ground pool, 20" sand filter, 2 HP pump. New Spider gasket & continually get sand back in pool on a yearly basis. Every year, I've had to change sand & underdrain assembly thinking this is the problem (Doughboy Pool, filter, & pump- no laterals with this filter) I'm thinking the pump is too big for my filter or the filter is a "lemon". I need help! Does anyone have any thoughts or answers? I'm at my wits end & about to bury it. But my "grandkids" don't want me to bury pool. Pool just 5 years old. Have had this problem for the last 3-4 years.