Last year I upgraded from a 2hp SP pump to a pentair 3hp VP inteliflow pump. My SD80 filter used to build up from 21spi to 30psi until I would backwash. Now even after running green shocked water through it for 4-5 days it still only increases pressure 1psi. and eventually the flow starts to slow. My sand is only 1yr old so I removed it and cleaned it and reinstalled it with no change I only get 1PSI no matter what speed i run the pump at. After many heavy shock treatments it is still green. Help
