From the Bru'nwater FB page....
pH METER RECOMMENDATIONS
Although using Bru'n Water reduces the need for checking mash pH, it is still useful to have a good pH meter available to double check things. Here are some thoughts for those of you interested in buying a meter.
A quality meter and probe are desirable, but high quality often comes with a high price. On top of that, buying a very expensive meter doesn't avoid the fact that pH probes DO wear out and have to be replaced. So moderating the meter price is a good idea. A meter that costs around $100 can serve well.
I recommend buying a meter with a resolution of 0.01 units that helps the user tell when the pH reading is settling down. Sure, you don't really need to know the pH to a gnat's a$$, but it's nice to know the reading is stable. In addition, a meter with a replaceable probe can extend your investment. For that reason, I suggest that getting a meter and probe that uses a BNC-type connector will allow you to replace the probe with widely-available after-market probes. I find that a meter connnected to the probe with a cable is a little more versatile than the all-in-one units.
Something you WON'T need on your meter is Automatic Temperature Compensation (ATC). That feature only compensates for the response of the pH meter's electrode with varying temperature. That feature does not compensate for the actual pH shift produced chemically in the mash. All mash pH measurement should be performed at room-temperature to avoid the measurement errors created by the temperature effects on the probe and chemically in the mash.