We have an in-floor cleaning system and lately the pop-ups have not been cleaning very well. There will be a star shaped area where the pop-ups have sprayed and rotated, but not really cleaned with any force. When we turn the system on, large bubbles of air come to the surface. We have cartridge filters that have been cleaned recently so that can't be the problem (we checked them again anyway) It seams like there is air somewhere in the system and we checked the seals and still no solution. HELP!!!