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Ask a Grower

Ask-a-Grower Question #79

How do I calibrate my handheld Hanna pH or Hanna combo meter?

It is the opinion of Hanna Instruments, as well as San Diego Hydroponics, that you should always carry out a two point calibration. For this you process you will need three small containers (around 60mL or 2 ounces). One container for water, one for pH 7.0 standard reference solution and one for pH 4.0 standard reference solution.

Now the steps for calibration:

1. Rinse the probe in water and shake it off.

2. Press the MODE button until the meter turns on.

3. Press the SET/HOLD button until the meter is reading in the pH measurement mode.

4. From the pH measurement mode press and hold the MODE button until the reading on the LCD screen goes from OFF to CAL. Release the MODE button.

5. The screen should now read “use 7.0”. Put the pen into a 7.0 standard reference solution. The pen will recognize the solution and self calibrate. When the screen changes to “use 4.0″ your meter will be calibrated to pH 7.0

6. Rinse the probe between standard reference solutions to avoid cross contamination. If you wish to only perform a single point calibration at this point press the MODE button and the pen will return to pH measurement mode.

To complete a two point calibration carry out this final step:

7. The screen should still read “use 4.0″ Put the pen into a 4.0 standard reference solution. The pen will recognize the solution and self calibrate. When the pen is calibrated the LCD screen will display OK for 1 second and return to normal measurement mode.