Wierd PH Probe Readings

[rschneider77]

I noticed that the PH values from both my client and phone app were reading extremely low, (around 1.6.) So I cleaned it with vinegar and recalibrating the probe and PH still read low. I thought that my PH probe was bad so I bought another PH probe from ReefAngel.

My new PH probe after proper calibration has values 554 (7.0) and 857 (10.0), and reads in the 5.0 range in the sump and aquarium. When the probe is placed in a cup of sump water it reads correctly, (7.9 range.) After reading posts about stray voltage causing the problem, I unplugged all pumps and ATO in the sump and aquarium. I placed the probe in the sump and the reading was in the 3.5 range. I then placed the probe in the aquarium and the reading was in the 5.8 range. Then I put the probe back in the cup of sump water and the probe read 7.9. I have no idea what the problem is. Any help would be appreciated.

Thanks,
Robert

[lnevo]

Did you remove the float switches?

[rschneider77]

No. I unplugged it.

[rschneider77]

I figured it out. After trouble shooting for 15 hours, the first new float switch I tried , the ph probe would read correct ph in a glass of water and not in the sump, the second new float switch I tried, the ph probe would read correct in a glass of water and not in the sump. The third new float switch I tried, the ph probe read correctly in a glass of water and is now reading the ph correctly in the sump. Two bad float switches, who would have thought,