Well, I have had a pH event over the last few days. It dropped so low I thought the probes might have been a problem, or some environmental factor, but when I loaded up some TLF, the problem was resolved.
It's kind of scary to think that the Custom Aquatic kalk could be doing fine and then suddenly hit a wall like that. Even scarier is the thought that my system is so reliant on it that when it went south, my pH dropped to 7.65 during the night cycle. That got my attention!