Proper care must be taken to ensure that your electrode continues to take accurate measurements. The tip of the reference electrode is porous glass frit or electro porous KT glass (opaque white). The frit allows ionic transport into the electrode. In order to operate properly the frit must always be kept wet with electrolyte.

Filling Solution

Both electrodes are filled with Saturated KCl. To fill the electrode, slide the rubber grommet located at the top of the electrode down. This will reveal a small filling port where saturated KCl can be added.

Storage

Both Ag/AgCl and SCE reference electrodes should be stored in just slightly less than saturated KCl solution. Keeping the solution just below saturation allows enough ionic flow to prevent salt crystals from forming in the glass pores.  The frit must be kept wet at all times to ensure the impedance of the electrode remains low.

Checking the Impedance of the Reference Electrode

It's very important for optimum potentiostat performance that the impedance of the Reference Electrode in your cell is low!  A high impedance Reference Electrode will cause problems that range from simple overloads to potentiostat oscillation.

https://www.gamry.com/support/technical-support/frequently-asked-questions/reference-electrode-overview-and-care/