When I vacuum, I see the fine dirt just blowing right by my filter out of the returns. I have a sta-rite s7m120 cartridge filter. There is no leak in the plumbing inside the filter, past the cartridges. The cartridges were brand new last season. There is a small cut in the screen on the air bleed filter. But I would think that dirt could get through that screen anyway. Do I likely have a hole in my cartridges somewhere? Or is the air bleed screen likely the culprit. Is there anyway to figure out which cart is bad if that is likely the problem?