I had noticed my 2 year old pH probe started acting glitchy despite recalibration, so I went and replaced it with a new probe. I was able to calibrate the probe and confirmed that it was reading both the 7 and 10 pH standards accurately. After a few days, the probe started with the same erratic readings (see image). Nothing was added to the tank at 1 am to cause the spike in pH. Measurements made yesterday were Alk=9.8, Ca=415, Mg=1260. Temp ranges between 77.5 and 78.3 F, salt between 33.3 and 33.4, and ORP between 390-400 in the past days. Any thoughts on the issue? Is this a problem with the Apex unit instead of the probe? How do I go about resolving this matter? Thanks!