It prevents the electrode from drying out and becoming inaccurate. You need this if you own a pH meter,_x000D_

My electrode is fine after 2 years of using this. Since the cap holds just a small amount this bottle will will last for years.

I used to store my pH meter in water but after a couple of years it wasn't very accurate. I replaced the meter and now I soak the electrode in this solution, which lasts since it doesn't evaporate in the cup.

I found out the hard way that you cab't store your electrode in water because it will gradually lose accuracy. Now I use this and since the cup is sealed it doesn't evaporate and this will last a long time.

You need to keep your electrode stored in this stuff to keep it from drying out and failing. Since I brew every few weeks I use my pH meter and constantly check that there is enough fluid.