16,000 gallon 14x28 IG Indoor Fiberglass pool with sand filter and pentair superflo pump.
After releasing the air from the filter, it takes about 15 minutes for the jets to start spewing (small) air bubbles. If I close the main drain valve about half way and leave the skimmer valve wide open, the bubbles almost immediately STOP.
I've removed the pump cap and checked to be sure the gasket was intact and everything looked good there.
What is going on?