A Craft Beer & Brewing Magazine reader recently asked us the following question:
I purchased an inexpensive pH meter to manage my mash pH, but I’m having a hard time getting consistent readings from it?
Managing your mash pH within the 5.2–5.6 range is important for all-grain brewers. While you can estimate mash pH and make basic adjustments using software, it is still important to have a good-quality pH meter to verify your pH. You mention that you purchased an inexpensive pH meter, and this could certainly be the source of your problems. Many low-cost meters are not terribly accurate, having variability of +/– 0.1 pH or higher. Very cheap ones may not be suitable for beer brewing.
Some of the features you should look for in a pH meter include an accuracy of +/– 0.01 pH, automatic temperature compensation, a good (digital or analog) calibration system, and—ideally—removable probes. Removable probes let you replace the pH electrodes, as these will wear out and become non-linear within two to three years for a typical unit.
A second source of your problems could be improper calibration of the unit. Any pH meter must be calibrated before use. To do this, you need to purchase a “pH Buffer Calibration Kit.” The kit contains three different solutions with a known pH of 4.0, 7.0, and 10.0. In addition, I recommend purchasing electrode storage solution, which is a solution you want to store your probes in to extend their life and maintain calibration.
For a digital pH meter, you simply push the calibration button and then put the probes into each of the fixed solutions when prompted, and the unit will measure each and calibrate the unit. Calibrating an analog unit is similar, but typically you adjust a different calibration knob for each of the known solutions.
What I recommend is to calibrate your unit using the known solutions and then wait a few hours and measure the known solutions again. You should get good readings from the unit as it should be able to maintain calibration for at least a few days if you properly store your probes in the storage solution. If you don’t get good readings from the calibration buffers, I would consider replacing the meter with a good-quality pH meter with the features mentioned above.
If you have a question for the experts or want to share your expertise, email us at [email protected] or visit our website at beerandbrewing.com.
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