I have calibrated my Apex PH probe in 5 different solution packs of 7 and 10 and after calibration its is showing 7.92 and I used two different test kits and both show 8.2. This is a brand new reef tank filled with RODI water and Red Sea Coral Pro salt. I had the same problem with my last reef tank which was up 8 years and the Apex was never correct so I just used it as a reference. Anyone have the same issue or a way to fix it?
