cavitation

I have a new pool build. 21,000 gal. 2.75 HP Hayward variable speed pump with Hayward 4 cartridge filter and salt generator. Not long after my pump switches from 85% to 50%, a small bubble forms at the top of the reservoir. The longer it stays at 50% the bubble becomes larger and larger until...

Anyone know if it is a bad idea to partially block the skimmer to create aeration/CO2-degassing? The pump seems OK with it (i.e. not hot or making noises) and I get the desired aeration bubble coming out the return jets. I guess cavitation could eventually do damage, but I was thinking this is...

I have 2 skimmers and a main drain. I was planning to do my own closing in the fall using the main drain to bring the water level down below the skimmers. However I just now tried running only the main drain and I get lots of bubbles/turbulence in the pump basket. Otherwise, with the skimmers...

Hope someone can help, I'm so frustrated. My 1hp pentair Super flo just died. My brother gave me a 1.5hp pentair Super flo he is no longer using. I am using it now and it makes the most dreadful noise. It chugs like a train and grinds. It is so loud I can hear it in my house. I don't know if the...