BillyZ - yep sounds reasonable - but pretty sure the PH
is 8.2 (besides, don't trust my LFS
too much - figured that when they pulled out a Wardley's test kit)
and that the monitor is not working - just not sure if it's the probe or the monitor. That's a reasonably expensive guess. I.e. replace the probe for $40, if it was the monitor, then buy a monitor with the probe for 89, then in just 2 years spent $220 on ph
monitor (two units w/probe for 89 each and one superfolous probe for $40) - Yikes!
As for the mfg - I believe they actually only suggest that you will get at least 18 months but that it should be replaced when it can no longer be calibrated. Even then you can never be sure - could be that the probe is fine and the monitor is screwed up. As I mentioned - just another complication.
Anyway - guess I'll try replacing the probe - but I am not going to be a happy camper if it turns out to be the monitor