There's a lot of talk on TFP about total alkalinity, and it's a routine test. The general literature on pools says TA is a buffer and a measure of the resistance of water to pH change. Elsewhere on here and if I recall correctly (I can't pinpoint the exact thread again), it says that TA is only a measure of the resistance to pH change downwards, while total acidity is the buffer against pH change upwards.
Why isn't total acidity routinely measured? Most people seem to have pools where pH keeps rising, so resistance to pH going up seems like a good idea.
What influence does CYA have? The mantra of the people who ran the pool before me is "you use tablets to manage your pH". They say that because the tablets are acidic, it helps to balance out the tendency for high pH due to having hard water. Late in the season this seemed to be true, but earlier on when overall CYA levels were lower, it didn't seem to work so well. pH would rise a lot during the day when the pool was in use, but settle back down overnight.
Where can I find out more? Thanks for being there to help.