On the other hand, higher T/A levels DO tend to stabilize pH, so the out-gassing should be less effective at raising pH when pH is already in the optimal range.

Yes, I did understand about the borates as an algaecide. While it couldn't hoit, I'm not sure it's necessary. Running a T/A of 80 I believe WILL cause bouncing pH--It's just not high enough to stabilize pH adequately.