Bluelab pH 4.0 Calibration 500ml
Save Liquid error (product-badge line 32): -Infinity%
Rinse probe in fresh water and place it in either pH 4.0 or pH 10.0 solution (use pH 10.0 solution if you expect to measure above 7.0 pH). Wait for reading to stabilize. Press the cal button until CAL 4 or CAL 10 is displayed CAL 4 or CAL 10 should be displayed (depending on what solution you are calibrating in).