Kurt Ullman wrote:

We also spent most of the summer chasing pH and alkalinity.

Salt water generators raise pH to about 7.8 due to the production of
sodium hydroxide and features like waterfalls raise pH by freeing up
carbonic acid. In this last case you may see a significant drop in
alkalinity when you r-eadjust the pH downwards.Do you have a SWG and/or
waterfalls/fountains?