Issue with PH Calibration

[pjcook]

I have just calibrated my PH probe for freshwater, I set the first level to 4 and used calibration solution 4 and the second level to 7 and used calibration solution 7. All went well with the calibration until I tested it. I placed the probe into the Calibration solution 4 and the unit measured it as 3.0, I then placed it into the Solution 7 and it is measuring it as 5.57. I would have assumed it would have measured them as 4 and 7 respectively.

[GHL Support]

It seems that the calibration process was not successful then. How old is your sensor? What are the ADC values?

[pjcook]

Hi

I have run the calibration twice and still the same issues. The unit is about 2 years old. The ADC Values are ADC 1: 530 ADC 2: 522

[Wirus]

I have run the calibration twice and still the same issues.

I suggest there was a beep and a message that calibration had failed.

The unit is about 2 years old. The ADC Values are ADC 1: 530 ADC 2: 522

Your electrode is defective. The ADC values are much to close together. It should be something around 700-800 and 440-500.

Your electrode only has 8 steps between ph4 and ph7 - much too less to measure accurate.

[pjcook]

Could well be the case as I was using the unit previously on a marine tank, there was no message that the calibration had failed but I take your point. I will order a new probe and see if that sorts it all out.