Question on my New pH Pen

Just got a pH pen (Vital Sine) and was surprised to see instructions were so sparse. Basically it says to "keep electrode in water at all times". Does this mean while not in use? I assume it does. So I guess that means I just take a glass jar, fill it to the "waterline height" (marked out on the pen) with tap water and put the pen in while not in use. It says never to use distilled or ionized water.

Was a really good deal ($18 from AES) but I wish they gave a booklet with specifics rather than just sparse info on the back of the package.

EDIT: It has a cap for the electrode section and frankly I'm wondering why they'd include a pocket clip if the electrode is supposed to be under water at all times? Looks like I've asked a dumb question, but better safe than sorry. Do I need to store it in water (just up to the top of the electrode section)?