PH Pen calibration - how do i?

[HigherTheHigh]

Hello all!

So i have a PH pen, its not the best of pens but iv just recently found out my PH in my local area has went from 6.0 to just over 7.0.

When i got it i turned the pin at the back without thinking but iv heard you need to do them every month, so how do i calibrate it to be absolutely perfect?

 

[Weaselcracker]

You need something with a known ph - basically what you need is ph calibration solution. The most common is neutral -7.
You put the probe in the solution and turn the adjustment on the back till it shows 7.
There are also ph 4 and ph 10 solutions and some people calibrate their meters with all three.