I run in GPM mode most of the time. I use RPM mode on the quick clean option set to calculated 3K rpm and I use that value to check DE filter pressure. With clean filter and 3K I have 20 psi at the filter. The air is gone when I have to booster on but returns in a couple of hours after I turn off the booster even running at 3K rpm.
The pump is only a few weeks old. I did remove and lube up the two drain plugs on the pump as well and took out the lid o-ring and cleaned/lubed it. The lid is different in that the clear part appears to be an insert inside of the ring that tightens the lid. It has an o-ring in it too, but I can't see how it would come out.
Is there any way that too large of a pump could be the issue? I was a 1.5 single speed Challenger and replaced with 3hp VSF. Pipe is 1.5" for the most part.
Are you able to continually expel air from the filter at the air relief valve? Do it once, come back a few minutes later and try again. Is it a lot or just a quick spurt? Seeing no air in the pot used to be the standard to judge by. Now, with VSPs, it isn't. You get used to it.
My VSP will, on a rare occasion, have no air visible in the pot, usually right after a filter cleaning. Most of the time it does show what appears to be some. Yet, I am seldom able to get more than a quick spray of air from the filter, even at low speeds.
I know my pool equipment, like most eventually, has a small leak somewhere that allows the filter to drain each day after the pump shuts off. There is never water anywhere. Some leaks will allow air in but are small enough to not allow water out.