Best PH Meter or Tester for Ferments

[Guest guest]

Someone told me there is a difference between making vinegar and making lactic

acid stuff. So, since I am new at this and would like to test the ph of my

experiments to ensure that I am not making vinegar. I read that paper ferments

are not reliable for home ferments. There are lots of testers and meters out

there, some pricey and they all seem to require maintenance like with

calibration and so forth. Can anyone recommend one that is affordable, easy to

use and reliable, and especially not too hard to maintain with the calibration?

Many thanks