How does a Ph probe die?

[Jimmy Orkin]

My Ph meter is acting strange. I calibrated it at 7 and 4. A couple of hours later when I was checking my mash Ph, the meter was reading 5.4 instead of the Bru'n Water prediction of 5.2.

My experience with Bru'n Water has been a very reliable predictor of Mash Ph.

So I ignored my meter, added the remaining acid BW predicted and went about my brewday.

After the brewday was over, I tested the 7 and 4 calibration solutions. They both read about .2 high.

Is the the normal way a Ph probe ends its life? When do you know when to replace your Ph probe?

[James Smith]

Probe easily going out of calibration I believe is a sign of failure. I have replaced my M102 probe once already.

[Jason Garland]

It is my experience that pH probes need to be used frequently or else they fail at a high rate. The tip just does not like intermittent use.