Problem with PH measurment

[dimbar]

Hello
I have problem with PH measurment, electrode is connected to expantion card
I have colebrated the electrode but in sea water ph is about 10.4, in RO water ph is about 4.8
i tried to change PH electrode but unsuccessfully

Have you any ideas?

[Matthias]

what are the ADC-calibration values?

[dimbar]

I will check today evening and let you know

[dimbar]

I am sorry for delay

PH 7 -ADC:0454
PH 9 -ADC: 0365

[Matthias]

these values let me assume that the pH-probe has passed its lifetime, you should have a difference of min. 200 ... 300 between 2 calibration

or you used accidentally the calibration fluids in the wrong order?

what pH value is displayed when you immerse the probe into fluid 7.0 and 9.0