If I close the skimmers and have just the main drain I get all that air. The water coming out of my returns were never as hard as it has been this year. Again, when the pressure starts to register in the 30's from the 20's it seems to clear up. It just seems like the water pressure coming out of the returns is way too strong.......the circulators should not be a concern, just mentioned I put them on and when you do the pressure on the filter goes up because as you say it causes a lot of back pressure. If I dont have them on and run the pump for so long and the pressure goes up because of being dirty , the same thing happens, the air dissapears.