Calibrating Digital PH Meter

[jimim]

So even when our water is 40 when we r closing in the fall and opening in spring. I thought we had to warm our sample up to what the meter was calibrated at or it can be too far off to be reliable. I know with the drops it doesn’t matter but I thought with meter it did. That was one of the reasons I stopped using it.

 

[ajw22]

So even when our water is 40 when we r closing in the fall and opening in spring. I thought we had to warm our sample up to what the meter was calibrated at or it can be too far off to be reliable. I know with the drops it doesn’t matter but I thought with meter it did. That was one of the reasons I stopped using it.

You need to warm water to room temperatures for reliable CYA tests. Never heard of needing to warm water for pH tests.

pH meters are used in all sorts of food, beverage, and chemical processing at a wide range of temperatures where accurate pH is more critical then in our pools.

 

[Arizonarob]

I think this yellow pH Meter is the best value and all we need for a pool. It is inexpensive enough to be replaced every season if necessary.

I agree Allen, I was just bustin Matt’ chops.

 

[JoyfulNoise]

Even so, a “good” pH probe will be one that says “automatic temperature compensated (ATC)” in the specs. While you don’t see much change in pH with temperature day to day using phenol red, the pH can vary by as much as 0.5 units from freezing up to room temperature. So ATC is important.

 

[jimim]

I feel .5 is a big range for us living 4 season regions. .5 deff affects csi range when temp is playing a more important role for calculating csi. At least I feel it does.

 

[Brad_C]

Even so, a “good” pH probe will be one that says “automatic temperature compensated (ATC)” in the specs.

Both my probes are ATC. The good one has the temperature sensor in the tip immediately adjacent the pH probe.

The cheap yellow one has an SMD NTC on the PCB just up from the pH probe. The issue with that is while there is a thermal sensor and it does compensate the pH readings, the thermal sensor is in a place where it takes 10 minutes to reach thermal equilibrium with the fluid. So yes, it's "ATC" but for all intents and purposes it may as well not be. Your calibration fluid should come with temperature compensation charts.

My TDS meter is the same. Has a temperature sensor, but it's in a position where it takes lots of minutes to reach equilibrium.

If you are really concerned about your meter and near freezing pool water, put some in a glass in the freezer and do side by side comparisons with room temperature water. You'll very quickly get a feel for any compensation required when taking measurements.

 

[jdlangley1]

Received PH meter today. Will see we how it works.