How do you lower pH in a vinyl pool with muriatic acid?

The only way to lower your alkalinity is to use a pH decreaser. adding acid will also do the trick but for vinyl pools it is easier to just use a pH decreaser ( which is acid) and then adjust the pH. Remember not to use expensive alkalinity plus...arm and hammer is alot cheaper and the same thing. It costs 1.87 for a 4 lb box.

Alkalinitywe haven't been able to get our pool clear...the alkalinity is soooo high and we are about to go nuts with tempt in 90's...HELP!