Calibrating my new PH meter

The main issue with this PH meter is not the meter itself, but the instructions! They look like they have been partially translated from Chinese! Fortunately, this is not a massive issue as it is a fairly simple device, however, when it comes to calibrating it you want to make sure that you have done it right! Particularly, if you haven’t calibrated a PH meter before.

So here’s how I calibrated mine.

• You need to acquire some test solution that has a specific PH of 6.86. Fortunately, these solutions have been standardised and you can buy small sachets of powder that you mixed with 250ml of distilled water to get a 6.86 solution (+/- 0.01 PH). Once made up the solution is good for a couple of months if kept in an airtight jar. I found the sachets on Amazon. Some versions of this PH meter seem to come with some of these sachets in the box.
• Put the probe into the 6.86 solution and hold the “CAL” button down for around 3 seconds. This starts the calibration process. The display then displays “CAL”, then 1 second later it shows the current PH, then 1 second after that it sets the current PH to be equal to 6.86. Then it displays “SA” for 1 second and then it displays “End” for another second. Then the meter goes back to displaying the current PH (which is 6.86)

Once it was calibrated, I used it to measure the PH through the major brewing stages. You will find the results here.

UPDATE: I calibrated my PH meter 6 weeks ago. I put the PH buffer solution that I made in the fridge (in a Kilner jar). So what is the meter reading now? A quick test shows that it is 7.35. Now the question is…is this the PH of the solution that has changed or the calibration of the meter?

Only way to find out is to make up some more buffer solution and find out. So, a newly made up solution shows that the meter has lost it calibration! It was reading 7.3 for a newly made up solution that should have been reading 6.86. I recalibrated it using the new solution and the old solution is reading 6.85.

CONCLUSION: The buffer solution seems to last a least 6 weeks, but it looks as if the PH meter needs to be calibrated fairly frequently!