pH Probe Question

[Kengar]

How often is it recommended that the Neptune Lab Grade probes be replaced?

Also, if it is getting old, will it take and "hold" calibration?

The reason I ask is that I'm seeing significant drop in my pH and am wondering whether probe is on its last legs.

[lvreefer]

Under normal use I believe it’s 12 - 18 months. The more often a probe needs calibration, the sooner it needs to be replaced. It all depends on how you take care of it and how accurate you need it. I replace mine when it needs to be calibrated more than once a month or >0.05ppm off.