Tonedeaf,
What is your current TA level? If you've been adding acid, then the TA should be dropping over time. Stop adding baking soda to raise the TA and just let it drop to see if the rate of pH rise slows down at a lower TA level. The Borates in the pool should act as a supplemental pH buffer letting you have a lower TA level.
Normally, the borates by themselves don't reduce the total amount of acid needed, but do slow down the rate of pH rise -- but when you do need to add acid, you need to add more to lower the pH back down. If there is nascent algae growth, then the use of borates can result in lower chlorine consumption and that lets one turn down the SWG on-time and that can lower the rate of pH rise.
So your situation is certainly unexpected and different from what most experience. Try a lower TA level to see if that helps. Also, check the FC level and if it's higher than the roughly 5% of the CYA level see if you can somewhat lower the SWG on-time.
Richard