Another Neptune pH probe calibration problem

[vessxpress1]

Hey everyone. I know there's a lot of threads on this and I feel like I'm well aware of all the suggestions coming. I got a brand new lab grade pH probe today. Took the cap off, rinsed it in RO water then shook off, dried outside and placed directly into a packet of 7.0 pH fluid that was sitting in sump temp acclimating for an hour. Manually calibrated. Took it out of that, rinsed in RO water shook off, dried and placed in the 10.0 fluid. It settled at 950. Took it out rinsed off again, placed in tank. pH reading is sky high. 9.36.

So took it out, ran through this again. Tested in the 7.0 packet and it reads 7 on the money. In the 10 packet it reads 10 on the money. Put it in tank and it reads 9.33. Check with Hanna meter and it's 8.6. I'm running a CO2 scrubber recirculating air on skimmer and just added some alk so I believe the 8.6 number. I don't believe the 9.33 but that's what I'm stuck with, with my new probe. Same high number the old probe was reading.

I'm aware of the wire interference issue and do not have the wire up against any power wires. I tested pH with a salifert test and it's most certainly at least 8.6. But it was reading over 9 pH with my alk dkH at 5.9, which I have since increased.

Back when I trusted the old probe, it was common for my pH to briefly hit 8.5 or 8.6. Would be 8.2 in the mornings. It stayed pretty solidly in this range. What do I try now?

 

[dank reefer]

Grab some tank water in a cup and place your probe in it and see if its the same number as when the probe is in your tank.

I had a UV sterilizer that would cause havoc with my PH probe until I re-ran the UV and probe wire so that they would not come close to each other.

 

[vessxpress1]

Tried that. Read exactly what it reads in the tank. Tried calibrating again and it says tank is 8.85. It can't be. Think I got a bad probe.