The Voltcraft PH-100 ATC is a handy pH meter with a resolution of 0.01pH.
the accuracy is +/- 0.07 (no specification on precision)
It's still fine for aquarium use, just don't be misled - though that's precisely what the description intends
Similarly check for statement of accuracy/precision for the pH standard solutions, also storage recommendation & life expectancy after opening.
Note that if mostly measuring pH between 4 & 7 use those standards, if most pH measurements will fall above 7.0, use 7 & 10 standard solutions for the calibration.
I suppose unless you spend £100s or even £1000s on a pH meter then there's always going to be a fairly wide accuracy / precision claim by the manufacturers.
When a meter is not in use I've read that you should keep them in either a pH Or distilled water ? Could you actually keep the sensor submerged in the aquarium? Obviously then carrying out calibration on say a monthly basis.
Yes just keep 'm stored with a few drops of nutral (ph7) calibration solution. regularly check if its not dried out. some have a cap with o-ring which is pretty tight, but the pocket ones don't and always dry out after some time, for those it's best to use a piece of cotton soacked in klc solution to store.
i have the best experience with Hanah instruments. Still got one over 10 years old and also the probe is and still working perfectly. No idea if they still make the same quality, but back than it also stated replace probe once a year.
My opinion, its a fail safe fairytale, just have a new spare probe ready for use, as long as the old one works no need to replace it. you have to check and calibrate regularly anyway.