Quote Originally Posted by Rickmart View Post
I've been using Cal Hypo shock in my inground, vinyl pool. The shock seems send my ph all over the place.
If you've been using Bioguard Stingy Sticks, you probably have been listening to them on what your pH needs to be. Get a good test kit, test your pool, tell us what you find, and THEN tell us what your pH readings are doing. It may well be that your "problem" is actually no problem at all.

However, it's possible to use cal hypo with very little pH movement. I used it continuously for 3 years on an indoor commercial pool, and during that entire period used only 1 - 2 gallons of muriatic acid!