Malfunctioning pH Probe

CheifReeferNB

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I have been struggling to get my Neptune pH probes to work on my system. The pH will randomly drift from a reasonable number to 12.2 over the span of 3-12 hours. I will unplug the probe and the display will continue to read in the low 12s.

I initially thought it was a faulty probe so I replaced it with a new one but the same thing happened. I tested the probe isolated from the aquarium in a small cup of tank water with no success.

Neptune systems has not been helpful basically saying they’ve never seen something like this before and it must be a setup issue.

Has anyone experienced this and can help identify what may be wrong?

Thanks!

20260604_092832_DD8C7D44-1221-472B-9ADA-C0B36F847842.png
 

Randy Holmes-Farley

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I tested the probe isolated from the aquarium in a small cup of tank water with no success.




20260604_092832_DD8C7D44-1221-472B-9ADA-C0B36F847842.png

Meaning it still drifted in the cup with nothing else in the cup?
 

Randy Holmes-Farley

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Sometimes, pH electrode readings are messed up by having the wires near other wires or electrical equipment.

Try separating wires if that might be an issue.
 
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CheifReeferNB

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commod0re

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when I was experiencing issues like this with my Atlas Scientific pH probe this is what they told me to try and it worked for me:

saturate a glass of water in pure NaCl salt and soak the probe in it for a day (24 hours) to restore the electrolyte and that worked great for me. For the Apex probe I think you should use KCl salt instead of NaCl. If it still acts a bit funny after that soak it in 4pH calibration solution for another 24 hours. If it still seems untrustworthy after that, replace it
 

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