I have an above ground pool with a 1 1/2 hp pump. I have replaced the laterals,replaced with new sand,installed a new "head unit and spider gasket. I will end up with a couple of handfulsof sand between each pool cleaning. The filter indicates it can hol.d 200lbs of sand. I placed 100 lbs of sand in the filter, because that was the previous level of sand which I have had in the filter for years. I have replaced everything I can think of. Is it possible that there is too much pressure from my pump, as this problem has only surfaced last year, and continues this year. Would adding more sand to the filter help? Thanks for any ideas, as I am lost.

The hub that the laterals fit into can have a crack and cause this, or the stand pipe that goes from hub to the multi port.

The valve or gasket, if bad will not cause sand to go back into the pool, it will allow dirty water back into the pool, or leaking out backwash port.