Plumber replaced shallow well pump in basement with submersible in 50' well. Also replaced anode rod in hot water tank. Ever since, I get air purging through line after short periods of not using water. I have taken a picture of pressure gauge before going to bed, then again six hours later in morning and there is not even a pound of pressure lost. Did this twice to be sure. Have put water softener on bypass before bed, purged any air from lines, then turned on water in morning while still on bypass and got plenty of air. So I think that eliminates water softener as source. Have pushed top vent on Big Blue filter and no air purges there. There is no evidence of any leaks anywhere. No leaking around anode rod fitting or hot water tank at all. And I'm not positive, but air seems to be mostly or all from hot supply. Pressure is set up at 30/50. Plumber says he thinks the new pump pushes water at such high velocity that it is seperating air from water. Problem is now two months old and no resolution in sight. Suggestions, please.