I recently moved into a house with a pool and everything was working fine. However, now the pool cleaner moves VERY slow and the pump psi is around 30. I have a Haywrd system with a cartridge. I have pulled out the cartridge and cleaned. When I clean I very thoroughly the system drops to about 18-20 psi but that only lasts about a day then it goes back to 30psi and moving across the pool bottom slowly. What can I do to get this system running properly? I have taken the cartridge to pinch a penny and they said that the cartridges fine and doesn't need to be replaced.