Last night I did my basic water tests before going to bed, only to discover my pH had bottomed out at around 7.5. It's consistently been low, usually around 8. I can't remember if I dip-tested the water Sunday when I did the water change, but it must've been off. Pretty mad at myself there. Anyways, I had some pH 8.3 Buffer on hand, which i mixed into some distilled water and topped off the sump with. This morning the pH is 8.1. I hope the violent swing didn't kill anything, but as of this morning, everything seems OK.