really cloudy water

[PoolDoc]

Borax increases your pH without screwing up other things -- if you have low pH, you want to fix that ASAP since it can tear up your pool.

Distilled water is for pH testing (and later, CYA testing, if you have high CYA). Phenol red pH tests only work up to 5 ppm of chlorine (10 ppm with the Taylor kits), but you can dilute pool water with distilled, lowering the chlorine, but not changing the pH much.