I purchased a new PM1 to measure the PH in my calcium reactor. I also purchased a new PH probe and calibrated it. The new probe is at 7.97 my existing PH probe is 8.15. So I recalibrate my existing probe and it still displayed 8.15. I then tested my water manually with two different test kits and they both showed the PH to be 8.15. So I recalibrated the new probe and it still shows the PH at 7.97. So my next step was to put both probes in the 7&10 calibration solution and they both displayed accurate readings of 7&10. Next I removed the PM1 completely from my configuration and installed it again and recalibrated the new PH probe again. It still reads 7.97? Again my other probe still reads 8.15 and I verified this reading with a salifert and Hannah test kit again. Both probes are within 3 inches of each other in my tank - I even switched their positions and got the same readings. I did have an old PH probe laying around and i calibrated it and it showed the same reading as the new probe. I also switched the probes around from the APEXel and the PM1 and the readings inverted so it’s got to be the PM1?
Any idea why the new probe is not reading properly - could the PM1 module be bad? Any other ideas?
Any idea why the new probe is not reading properly - could the PM1 module be bad? Any other ideas?