Ph meter calibration - readings

[VirginiaHops1]

I got a new ph meter this year, an Apera PH60. Not top of the line but I think it's pretty good. It has 3 point calibration but I typically just do 2 point because I only ordered the 7.0 and 4.0 liquid last time. I calibrate before every batch.

Yesterday I did the 7.0 calibration then took a mash reading(5.75), then did the 2nd point calibration with 4.0 liquid and did another reading(5.35). Is it normal to have that much variance between 1 point and 2 point calibration readings? I'm assuming not and the calibration fluid was not doing it's job? I'm starting to wonder if measuring ph is even worth the hassle unless you have a top of the line meter.

 

[day_trippr]

The PH60 is actually a very good handheld pH meter.
And you really need to do at least a two-point calibration to get usable data out of it, like any pH meter, with the two points on either side of the expected range of samples....

Cheers!

 

[VirginiaHops1]

The PH60 is actually a very good handheld pH meter.
And you really need to do at least a two-point calibration to get usable data out of it, like any pH meter, with the two points on either side of the expected range of samples....

Cheers!

Thanks, yeah I always do two point calibration with it but wasn't sure if the variance like that was normal(and I could trust the 2nd reading) or an indication that something funky was going on.

 

[VikeMan]

Yesterday I did the 7.0 calibration then took a mash reading(5.75), then did the 2nd point calibration with 4.0 liquid and did another reading(5.35). Is it normal to have that much variance between 1 point and 2 point calibration readings?

The meter needed that second point to determine the calibration slope. As an analogy, recall your 10th grade geometry class: you can't define a line with only a single point.

 

[ScrewyBrewer]

The Hanna HI98121 pH tester I use requires calibration using buffer solutions of pH 4.01, 7.01 and optionally 10.01, but there are other pH meters on the market that require 4.0, 7.0 and 10.0 buffer solutions for calibration.

For brewing water I calibrate my pH meter using the 4.01 and 7.01 buffer solutions because the mash pH measurements taken will all be within that pH range. I usually target the 5.3 to 5.5 pH range when preparing my brewing water, measured at room temperature, and the pH of my finished beer typically measures in the 4.3 to 4.5 pH range.