Review on Cole Parmer Combination Electrode Refillable Double Junction by Rodney Mendoza

I use these to maintain pH in my pool. I've always used calomel probes, but they're getting harder and harder to find due to mercury phobia. It's time to find a replacement. I calibrate my sensors in a buffer that has been heated to the same temperature as the spa (96F) for maximum accuracy. For comparison, I also run three meters at the same time. In short, after considering all available options, he settled on three candidates; this compared to 55510-06 and 05991-22. The 05991-22 actually worked quite well and was cheaper than this one, so I could use it for room temperature applications. However, in a heated pool, the readings will not stabilize until the sensor has warmed up in the water for about 3-5 minutes. Although the 55510-06 was the most expensive and was described as "highly accurate", it took the longest to stabilize and lost calibration very quickly. The 05991-22 took a few minutes to stabilize while warming up, but it stays accurate for a very long time. This one, 59001-34, appears to be very insensitive to temperature. It is read accurately almost immediately and practically does not change when warmed up. The calibration also holds up well. I was pretty impressed. It can be better than calomel if it has a good lifespan.