–Played with pool controls. (1) Main pump needs 2900 RPM to eliminate solar bubbles. (2) Booster pump needs ~2000 RPM for same. That is: 2900 + 2000 = no bubbles; 2800 + 2000 = bubbles; 2900 + 1500 = bubbles. Will try to tune the booster pump later. (3) Low water level leads to air bubbles in skimmer, which show up in main pump porthole (and pool inlet). So: sufficient water + sufficient RPMs = no bubbles. Again, it’s super-annoying that none of several techs provided this solution.
–Went to Bel Air for apples, milk, cream, dessert, etc.