Didn't catch a ph drop due to carbon dosing, I was too busy with an outdoor project to keep on top of things like normal. By the time I caught it, 2 days, stuff rtn'd.I had a few issues with some colonies, but water tested ok, didn't test ph, never had issues in the past, but the slow increase in carbon source, pushed ph down.
At least that is the only issue I could find.There may have been other issues, but none I could readily identify.