Ph Meter

I recently bought a Checker 1 Ph meter - - it seems to be working great, but how often should I be calibrating it? Also, can I buy the calibration solution, use a small amount of it and save the rest for future uses?

I recalibrate my Hanna 98127 with a two point calibration every two months. Its always within 0.1 when I go to recalibrate. I keep it stored in storage solution.
I have gone to buying the bottles of buffer sloution to calibrate instead of the sachets. I just pour a small amount into another container to calibrate and pitch it when finished.

Excellent information as usual, Baratone!