I have been running the pump 24-7. Everytime I open up the air valve thingie (technical term) on top of the filter it seems like air comes out of it for like 5 minutes at a time. The pressure gauge moves a little bit, but not all that much. Everthing seems to be working correctly. I have great pressure out of the return and it doesn't seem like the skimmer is sucking in air. Also, last year when I would open up the air valve, water would just spew out after the air was out, but this year it only trickles out. Any idea why it does this and how I can fix it?