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.