Just wanted to throw up a quick tutorial on how I calibrate the pH meter I use for checking my homebrew mash pH. I calibrate it before every reading. I know it is probably a little over-kill calibrating it that many times, but the meter was pretty cheap on Amazon and calibrating it is easy. The accuracy is +/- .1 so if I am able to get it to 5.3 or 5.4, I am happy.
I begin my removing my sample after the mash has been mixed well (Glass 4)and set for a few minutes. From right to left, I have some distilled water in Glass 1 and a small bottle with distilled water to help rinse the probe. I change out the distilled water in Glass 1 if it gets cloudy. Glass 2 has the 7.0 buffer solution and Glass 3 has the 4.0 buffer solution. Glass 4 has my mash sample and it is time to get started.
I begin by rinsing the pH meter in the distilled water (Glass 1) for a minute. I then place it in the 7.0 buffer solution (Glass 2). Make sure your meter is turned on.
The reading is .1 off so I use the screw adjustment on the back of the pH meter to adjust. You will have to see which way adjusts your meter up or down, but it only takes a very small amount of adjusting to get it where you want it.
After slight adjustment:
Once that is set, I rinse the probe in the distilled water (Glass 1) and then use my little bottle squirter to rinse it again before the next reading.
Once the meter is rinsed with the squirter, I shake off the excess water and place it into Glass 2, the 4.0 buffer solution:
The 4.0 check was good to go. Now time to check the mash sample. The sample was still warm so I cooled it to room temperature. The instructions did not say what temp exactly (room temperature) so I just made sure all glasses were about the same.
After it is cooled I checked it with the pH meter and BAM!
5.4 is within range so I was stoked. I had some lactic acid on standby just in case I needed to lower the pH. To lower the pH if needed, I would stir in 1 ml or 1/4 tsp at a time to your mash and check the pH again until you reach your target pH. If I had to raise the pH, I have baking soda or chalk (calcium carbonate) on standby and would add the same amount until it was where I wanted it..
That is it. It goes pretty quick after you do it once or twice. I would recommend you practice calibrating the pH meter a couple times to get used to the process. If you have to adjust your pH, you want to do it as soon as you can.
I will be using this meter until I can pick up this one by Hach. That is the same brand we use in the water lab at work. HERE is another option for $20 and Prime that is better than the one I have. Cheers!