Is someone having a Mac attack?
Anyway, fortunately I didn't change any settings. I did unplug the power from the controller unit and when I plugged it back in the problem was gone. It came back yesterday morning, so I unplugged it again and it didn't fix it this time but was fine by evening. Now the controller and aquanotes download agree, but the pH probe is reading very differently than my Reefkeeper probe, so I need to calibrate both of them before I troubleshoot this any further.
In the middle of all of this, a weather inversion hit the valley and is wrecking havoc with my pH! The checkvalve on my kalk reactor also failed and broke my ATO pump. This manual dosing and topoff stuff stinks!