Cleaned my buddies cartridge filter today, operated the system and open air valve for approx. 1 hr. I get no water flow from top of filter housing, just air. zero psi when air valve open, that's normal but when I close it I get good flow back at the returns and I get 10 psi at the gauge. It was 30 psi and very dirty before I cleaned it.
My question is it OK not to get water flow out of top when open? I guess the water is not reaching top of filter housing. But, like I mention above that I am getting good flow back at the pool, with no bubbles at the returns.
Picture below with valve open after 1hr, just air no water.
Picture below with pool running normal configuration, air valve closed.