Storage Requirements: To ensure a quick response and free-flowing junction, the sensing element and reference junction must not dry out. Always clean the electrode before storing it. Short-term storage (up to one week): Soak the electrode in pH electrode storage solution, Cat. No. 910001. To prevent crystallization of the filling solution, cover the fill hole whenever the electrode is being stored and open the fill hole when calibrating and measuring. Long-term storage (more than one week): Fill the electrode and securely cover the filling hole. Cover the electrode with the protective glass tube containing a few drops of storage solution. Before returning the electrode to use, prepare it as a new electrode.