I just rinse it off under the running tap once every 4-6 weeks. No need to
put it in storage solution, just put it back in the tank..

as for refilling them, what would you fill it with? They don't have
anything in them to refill.

and for calibration, just get yourself some calibration fluid and use it
according to the directions on the ph meter. I use 4 and 7. I put it in
the 7 and then adjust the 7 screw until it is correct and then use the 4 and
adjust the 4/10 screw until it is correct. Rinse with ro or distilled water
between testing fluids. If you don't have ro or distilled water just rinse
it under the tap and make sure you shake it dry.

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Margolis
http://web.archive.org/web/200302152...qs/AGQ2FAQ.htm
http://www.unrealtower.org/faq