Regardless of what the advertising says, please be advised that no one
makes a pocket pH tester that will give you reliable results week after
week for months on end.
Every pocket pH tester on the market has to be calibrated once a week or
so, and that means buying "pH buffer solutions" from the company that
made your tester. All a pH buffer solution is is a liquid with a
accurately known pH, and they typically make them in pH 4, 7 and 10.
You put your pocket tester in the pH=4 buffer solution and turn one dial
or press one button until the tester reads 4. Then you do the same
thing with the pH=7 buffer solution, and adjust the dial or push the
button until the meter reads 7.0. That's it. Now your pH meter is
properly calibrated, and will take accurate readings for a week or so.
The preceding is how you'd calibrate a pH tester if you're typically
measuring the pH of acidic liquids, like wines or juices.
If you're typically testing alkaline liquids, then you'd do the same
thing, only using the 7 and 10 buffer solutions, which are neutral and
You're supposed to throw your buffer solution out after each calibration
because they say you supposedly can't use it more than once...
..but that don't make no sense to me because all it is is a liquid with
a known pH, so why would the pH of the buffer solution change just as a
result of testing it?
Also, I have yet to have anyone explain to me why I even need to buy
buffer solution. If I calibrate my meter accurately, and then measure
the pH of Tropicana Orange Juice as 4.9 and Parmalat Homogonized milk as
11.7, why can't I then keep using Tropicana Orange Juice and Parmalat
Homogonized milk as my buffer solutions, and simply calibrate my meter
so that it reads 4.9 and 11.7 respectively, and that'd be good enough.
Yes, you'd have to keep checking to make sure that the pH of the
Tropicana Orange Juice or Parmalat Milk you're buying isn't drifting,
but after testing the pH, you can at least consume these things so the
testing doesn't actually cost you anything, whereas no one is going to
drink the buffer testing solution.
Hach Company also makes pocket testers for pH, total salinity,
temperature and all of that kinda stuff. I expect they're no better nor
worse than Hanna's pocket tester; both companies are big names in the
field of pH testing.