phprobe

My last pH probe broke during a move so I got a new one, but until then never had any problems. I've had the new one calibrated and running for about two months and then it started to drift upwards. This past week it drifted all the way to 9, which I hope was about 0.5 off. I did a 50% water...

So my PH and ORP probes both produce these strange drops at random times through the day, then pop back up to the correct reading. My PH probe was calibrated twice two days ago with 7 and 10, and is showing the correct PH reading. Both of these probes are sitting in the third chamber of my sump...