Every month (weekly recommended) you should check the EC calibration. Clean the face of the probe. Remove the shroud from the end of the probe and use a little kitchen liquid scouring cleaner such as “Jif" or "SoftScrub” on a clean “Scotchbrite” nylon scouring pad. Alternatively, use 600 grit wet-and-dry paper with the cleanser. Use a circular motion to scour the face of the probe and then rinse well in running water. Do not touch the face of the probe but shake off any residual water.
Replace the shroud and then place in the calibrating solution. The solution supplied has an EC of 2.77mS/cm (CF=27.7, ppm = 1382). Allow about 5 minutes for the temperature compensation to fully kick-in and then press the menu button to get down to the Calibrate screen. Then press “Enter” to get to the Calibrate sub-menu where you will again press menu to step through this sub menu until you reach the “Calibrate EC” screen. Then press “Enter” again, to get into the “Calibrate EC screen”.
Now press either the UP or Down arrow keys to get the calibrated reading to correspond with the Standard calibrating solution (normally 2.77mS/cm, 27.7CF or 1382ppm). When this is achieved, press the save button to save this in permanent memory.