How Calibrate A Hydroponic pH Meter

Using an electric pH meter is an easy way to measure your hydroponic nutrient solution, but it will need to be calibrated on a regular basis in order to make sure it’s giving the proper readings. Luckily, it’s easy to calibrate your hydroponic pH meter.

How to calibrate hydroponic pH meter

How Often Should You Calibrate Your Hydroponic pH Meter?

The more you use your pH meter the more often I would recommend calibrating it. If you use it daily you should calibrate it once a week. If you use your pH meter more on a weekly basis then you can get away with calibrating it once a month.

What You Need To Calibrate Your Hydroponic pH meter

In addition to your electronic pH meter, you will also need calibration solutions and some small plastic containers to put them in. Electronic pH meter calibration is typically either 2 point calibration or multi-point calibration. This refers to how many buffers solutions are used to calibrate the pH meter.

If your hydroponic pH meter is the type where you have to manually calibrate it, like the one shown below, then you will also need a small flathead screwdriver to make adjustments. Some electronic pH meters will come with one.

Clean/ Rinse The Probe Of The pH Meter

Before calibrating your pH meter, it’s a good idea to look at the condition of the probe and make sure it’s clean. Your checking to make sure there are no cracks and everything looks like it is in working order.

If there is not build on the probe up you can just rinse off it off. If you want to clean your probe, you can also purchase a pH Probe Care Kit that comes with a brush, cleaner, calibration solution and containers.

Calibrating Your Hydroponic pH Meter

Before calibrating, it’s best to read the manufacturers direction for the specific model of pH meter your using. Fortunately, most basic pH meters work about the same. The main difference is the manual calibration, using that small screwdriver discussed earlier, or electronic calibration, where the pH is calibrated with the push of a button. I’m using a basic model pH meter that has calibration screw on the back.

calibrate ph meter

Pour a little of each of the pH buffer solutions into small plastic containers. It is important to use clean, separate containers for the buffer solutions to avoid contamination. I use a pH meter that uses 2 point calibration and there were some packets of each ph buffer included.

pH buffer solution

Turn on your pH meter and place it in the pH 7 buffer solution wiggling, around a bit.  For pH meters that calibrate electronically,  you may need press and hold the “mode” button or “set/hold” button on your meter first. The reading will bounce around for a few moments. When it stops, it is ok to calibrate the pH meter. For a manual pH meter, turn the screw until the meter has a pH reading of 7. For electronic calibration, you may have to select a “calc” button.

Next, it’s time to calibrate the pH meter using the pH 4 buffer solution. You’re going to repeat the same process as above. Again, you may need to press and hold the “mode” button or “set/hold” button on your meter first. The reading will bounce around for a few moments. When it stops, it is ok to calibrate the pH meter to the pH reading of 4.

You should now have a calibrated pH meter!

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