Care and Use of pH Meters

A pH meter is really a voodoo machine with its various electrical and chemical mechanisms. So it's no wonder that they require special care.

pH meters can easily suffer a shift in their calibration and then all your readings could be in error. So calibration prior to each use is important. My meter is fairly stable, so I only calibrate once prior to each brew day.

The first thing to do is warm up the meter. I find that 10 minutes of warm up helps settle down my meter. Then it's ready for the calibration procedure.

pH 4 and 7 calibration solutions are needed for working with a meter for brewing. Since these solutions have a limited life, I use 'capsules' of 4 and 7 buffer made by pHydrion that are added to distilled water to create fresh calibration solutions. They will keep for 6 to 12 months when tightly capped. This is a less expensive way of maintaining fresh solutions. Although refrigerating the calibration solutions will extend their life, it is imperative that the solutions be at room-temperature (20C to 25C) before use.

Some meters have specific calibration requirements. However, most calibration is conducted by checking and setting the meter in the 7 solution first. After trimming the meter to read 7.01, move to the 4 solution to dial in that range. Repeating the 7 and 4 checks is recommended. Of course, rinse off the probe with distilled or RO water to remove all traces of the preceeding calibration solution. I recommend blowing off the bulb area of the probe by mouth to move excess water out of that recess. Then blot the probe dry with a paper towel before inserting probe into the next solution.

To reduce the volume of calibration solution used, use as small a container as your pH probe will fit in to for the calibration checks. Fill that container with enough solution to fully submerge the bulb of the probe. My probe is small [there, I said it ;-) ] and I am able to use the small caps of my buffer storage bottles as the containers for my calibration checks.

After the calibration is completed, discard the used solutions. Do not return the used solutions to their bottles since that could alter their accuracy.

The meter is now ready for use.