I have a 13000 fiberglass pool vacuum cleaning with 4 cartridge filters.. I was concerned my sweep may not be working right so I unhooked it from the hose, and used a manual ( me) sweep. The shallow end had a lot of dirt in it. as soon as I began to suck it up which the manual worked well.... the dirt just blew back into a return jet.so..... I just cleaned my filters but they are not new as a matter of fact 2 are over 5 years old. So what do you think? Thanks Dave