I have a new IG pool, ~20,000 gal and went with a 1.5HP Hayward Northstar pump.
When the pump is running at high speed, the pump is full of water, however, at low speed it does not fill up.
The pump is about 70 feet from the further skimmer - 35 from the closer, and I have a bottom drain as well. 1.5 inch lines. Two returns.
Any idea what is going on? Am I losing energy efficiency if the pump has air in it? (Strangely, there are no bubbles noticable in the return.)