With my pump setup the pressure on the gauge doesn't rise enough normally to tell when the filter is dirty and needs to be cleaned. Normal pressure on my variable speed rig at 1500 rpm is 6psi. When I crank the pump up on a clean filter the system pressure is around 16psi and not much higher (17 psi) on what I'd consider to be a fairly dirty filter after a month of service. I have two identical filters and just swap them each month for convenience. After swapping them, I clean the dirty filter with a hose, let it air dry, then put it away for the next swap. Sound about right?
Also, how do you folks determine when it's time to time to actually replace the filter rather than just clean it up? Physically, my filters both still look good. If they were torn or had bands coming off it would be obvious that it's time to replace. Are there any other indications?