My storage solution also states that it’s KCl. And my probe explicitly called out that a white salt crust may form. I assume that was to reduce support calls. [emoji846]
I get the white crystals also. I believe they’re a sign of evaporation of the storage solution itself. So I made a habit of checking and refilling the storage solution often.
Potassium chloride is neither an acid nor a base. So the pH of an aqueous solution of potassium chloride (KCl) is 7. and to reinforce the previous comments, the crystals are solid potassium chloride which come from the evaporation of the storage solution.