Tip from Neptune: Once you remove the caps off your probes. Leave them soaking in RODI water for a few hours, then install and calibrate.
Also, before you re-calibrate, do the same. Soak in RODI water, air dry, then calibrate.
I’ve read that you should never use RO water to clean, soak or store your ph probe?!
Now I’m confused.
Here is just one example from Hanna:
“Using pure water (such as deionized, distilled, or reverse osmosis) is also a major mistake when storing your pH electrode. This happens most often when someone runs out of storage solution but wants to keep the electrode hydrated. This, however, creates a bigger problem.
Deionized water contains virtually no ions. The pH electrode is full of ions, both in the filling solution and in the hydrated portion of the pH sensing glass. So when an electrode is submerged in a solution that has no ions, the ions in the electrode will want to move out into the solution in an attempt to establish an equilibrium. Over time, most of the ions will leave the electrode, rendering it useless. The glass will also degrade much faster, leading to shorter electrode lifespans.”