hold up folks, the sticky on Spas sections says that high alk makes it hard for ph to change, so i guess the quote i have in my post below is correct:
How do I use Chlorine in my Spa (or pool)?
"
Alkalinity is a pH Buffer. High levels of TA will not allow pH to change from additions of acid or base"
I always understood it to be borates that buffer PH. In the ABC's of Pool Care, it mentions this:
TA - Total Alkalinity - Appropriate levels help keep the PH in balance. High levels can cause PH to rise. (60 to 120, sometimes higher)
Pool School - ABCs of Pool Water Chemistry
Pool School - Lower Total Alkalinity
Strange that your quote says that, while the other articles say the opposite. Must be a mistake. I think they meant Borates.
Edited to add:Read the article quoted, it looks to have been written when TFP was first started.