Both. The pressure on the filter drops and the pressure or suction drop too. Prior to the drop when you put your hand over the area where the vacuum hose would goes the suction is so great it almost feels like it could suck your hand into the opening.
I'm having a problem with pressure dropping sufficiently when trying to vacuum the pool. Does anyone have any suggestions of why this is happening? And can you recommend any pool repair company in the phoenix, arizona area?