AnnaE:
It all depends on your water. If your CYA is low and your pH is high, the pucks in your chlorinator will help both. But if your CYA is too high and your pH is low, the pucks will exacerbate the situation.

Automatic chlorinators that use pucks are not "set and forget" systems. You have to test your water weekly for CYA...and you should be testing your pH daily, or at least 3 times a week.