I have the HACH PocketPro Plus. It is about 15 months old, and I've used it about 6 times. I'm getting what I assume is drift. I put it in the calibration solution and it will slowly drop over the course of 20-30 minutes about .5. Yesterday, the calibration for 7.0 started around 7.26 and ended at 6.75. I exited the calibration and then calibrated the 4.0 solution. Saved and then measured the 7.0 solution. It dropped and stabilized at 6.83.
I've never cleaned it, so assume that is the problem. Let me know if that is not the case.
I have always stored it with a couple of drops of RO water in the cap. I use it only for homebrewing.
I've seen recommendations in this and other threads to get the manufacturer's cleaning solution. Looking at the Hach site, I get
this, but it has a picture of several different solutions, and reading the Hach pH ELECTRODE CLEANING & MAINTENANCE GUIDE hasn't set off lightbulbs above my head either about what exactly to get for cleaning. AJ has stressed getting an enzymatic cleaner, but I've not seen anything with that description on the Hach info.
I need to order something. Anyone have specific recommendations? I saw one recommendation for
this, but I don't know if this is optimum. Not that I need optimum - sufficient would be acceptable.