Hi Troy! Prior to working for CropKing I made the mistake of thinking that using the temperature probe on the Bluelab Pro Controller was the proper way to calibrate the pH probe. Once I started at CropKing and reviewed the product manual, to be better able to assist customers, I realized I have been calibration the pH probe incorrectly. On page 16 of the Bluelab Pro Controller Manual under the “To carry out pH Calibration” it states: “The conductivity probe is required to be in the solution to ensure accurate pH calibration and measurement. The solution temperature is measured with the conductivity probe, not the temperature probe. “

@@CropKingInc Hi As taken from page 16 in the manual, its temp probe in with the PH prtobe to calibrate . pH 7.0 calibration a) Rinse pH and temperature probes in fresh water and place both probes in a small amount of fresh pH 7.0 calibration solution. b) Press and hold the pH measurement button and wait for PH CAL to be displayed. Release button. c) PH 7 and the first ‘[]’ will flash on screen. Calibration in now in progress. d) When all 4 ‘[][][][]’ have appeared, PASS or FAIL pH 4.0 and/or pH 10.0 calibration a) Rinse pH and temperature probes in fresh water, place both probes in a small amount of fresh pH 4.0 or pH 10.0 calibration solution. b) Repeat the calibration steps above using pH 4 or pH 10 solution. c) If a 3 point calibration is required, (you are expecting to measure both above and below pH 7) repeat the calibration procedure with the remaining solution value. The Pro Controller is now calibrated, and ready for use. will be displayed. PASS indicates a successful calibration at pH 7.0, and the pH 7 LED will be displayed. If FAIL is displayed, see section 6.0