maxepr1 said:
HUH??? If I understand this right, if I add 1 gallon of acid every 7 days your saying that I will add 1 gallon every 14 days isn't that a 50% cut?
No, the same total amount of acid. Say you were adding one gallon of acid once a week before. Adding borates might allow you to add two gallons of acid once every two weeks. Before, without borates, the PH might have varied from 7.2 to 7.8. If you let it go for two weeks the PH would get out of range. With borates the PH change is about the same, 7.3 to 7.8 this time, but over two weeks instead of one. The PH changes more slowly, so you can go longer between acid additions. However, the amount of acid required to change the PH is greater. Acid is added less often, but more acid is used each time. The total acid usage is the same.
To reduce the total amount of acid required something else needs to change. Normally lowering the TA will do it. Without borates you can only lower TA down to 60, which isn't always enough. With borates you can lower TA down as far as 40, which is almost always enough to stop PH increases. Of course, if you have plaster less than a year old, the PH will still go up.
My pool numbers are:
FC 4 to 6
CC 0
PH 7.6
TA 50
CH 80
CYA 80
Borates 50
Salt 2900
My PH is completely stable. It has been at 7.6 since I opened in May, and was at 7.7 most of last season. My fill water TA is 60, CH 70. I last added acid in early June 2010.
Not every pool will work at these numbers. If you have more aeration than I have you may still get a little PH drift at these numbers. If you have high TA fill water, you will need to add acid to counter the high TA fill water. If you have plaster less than a year old, the PH will go up no matter what you do.