Plain tap water stabilizes at about 7.2.
I did a 75% PWC. Used water from the outside spigot, bypasses are neutralizer, because I'm starting to wonder if the calcite from the neutralizer is having some kind of an effect with something.
I'll give the pH a day or two and check it, and if it still goes up I may just try to let it be and see if I can keep it stable and see what happens.
On a sidenote, I had to add more ammonia to try to keep the fishless cycling going. I might've added a touch too much, it's testing a bit over 4.0 ppm, but still seems to be less than 8, which is the next color category On the API chart. Is that probably OK if I just leave it be?