Thanks Richard.

Just as a follow-up, my swimmer load has always been just a couple family members, I don't use any kind of fountains, it has not rained in a month, I have not used Trichlor or Dichlor in years. I always take my readings in the late afternoon (shade). I do get a few leaves every now and then, but nothing abnormal.

Is it possible that the decrease in pH after I added borax was due to my new liner? As I stated in my original post, I put a new liner in this spring filled, with fresh water and added CYA to 25ppm. I know the CYA caused the initial pH drop, but after I added the borax could the liner (being plastic) have some kind of ion exchange going on that would cause the pH to decrease until a balance was reached? I used to work in a chemical treatment plant and know that ion exchange resin is made of plastic and even earth can have some ion exchange properties. I was just wondering if something from the liner could have caused this until it reached equilibrium.

Thanks again for your insight.

Jim