Actually, if it's cavitating then increasing the discharge head (plugging a hole or reducing the hole size) would make it better not worse. If you're really using the booster pump and not the main pump it may indeed be cavitating because they are designed for more pressure at lower flow.

I might try to plug a hole or two then. Not really sure how to do it though... Sure something will come to mind. Maybe just some white silicone, but first I'll see if plugging the holes takes care of the pump noise.

In any case, I think this thread is no longer needed My original problem is solved and I just need to start general care of the pool I have an aerator to raise pH, muriatic acid to lower pH and TA, and bleach for chlorine.

Thanks everyone!