When I vacuum my pool, I vacuum on filter (I think I'm supposed to be vacuuming on waste, but with only 5,500 gallons, it drops my pool level fast. Anyway, I noticed this evening that many of the smaller insects (ants, etc) were coming back through the return. It seems to me like the sand should be trapping them. Is this a symptom of a problem? I know SOME filtering is going on, because when I backwash the water runs dirty then clears and the pressure drops back to normal.
I installed a new spider gasket and handle spring about 2 months ago. I also took the valve assembly off to check for channelling, but didn't see any channels.