my hayward sand filter E100 rated 47GPM, my pump is 1.5hp hayward power-flo has 75GPM on motor lable. this is my sand in bottom of pool problem I think. if I go down to 1hp motor can I use same pump or is the GPM the pump or moror size. the pump its self has no GPM on label. thanks , this is my first sand filter. I think they shipped me the motor for the larger filter. pool was installed in june,09 so only 1mth old. bought pool from going out of business sale, so can;t take it back.