Hanna dKH Checker / Calibration Check Set / Trust it or Not ???

[piranhaman00]

Why would it matter if it’s calibrated to 8 or 5 or 2 or 15? If it’s calibrated, it’s just that. All that matters is if it should read “x” using the calibration set and it does.

This is wrong.

The instrument could be dead accurate at 5.0 but be way off at 10. Just because it reads at accurate at one point doesn’t mean it’s accurate everywhere.
The standard should be as close to your value you want. That’s why pH meters are calibrated in sets that bracket known results. A pH meter calibrated with 4.0 and 7.0 buffers will not be accurate at 10.0.

 

[X-37B]

I use hanna, salifert, and elos as a sort of triple check. Hanna is used 90% of the time. All are within .3ish of each other. As long as the Hanna remains the same I am not going to worry. Stability with the number is what im after with a hobby grade test kit.

 

[GoVols]

I hope folks realize that this sort of "calibration" does not by any stretch of the imagination demonstrate that you get accurate readings from the Hanna. It should be called a color standard for checking the electronics, not an alkalinity standard, which would require adding reagents to it and using the normal alk check procedure.

Thanks Randy,

Just glad I bit the bullet for a new alk checker (saved the $20), and it proved the second one was wrong from day one.

The new one stays within .2 with salifert, alkatronic and the first alk checker that I owned.

 

[taricha]

The hanna color standards verify than the checkers read a liquid absorbance as within a certain tolerance of what they should. It doesn't prove linearity of the instrument or that the chemistry packets are correct. It just catches really egregious failure of the optics I suppose.
That said, I've run a handful of hanna checkers across their entire range and never found even a slight hiccup in linearity. So if you have it operating as expected at zero and at 5.0 dkh then it's really likely to be operating as expected at 10dkh as well.
(BTW, a fun exercise - see how much pigment (drops of tea or something) you can add to a blank and still get a checker to read zero. It'll give you a feel for the built-in protection the checkers have against false positives. Then once you get a solution that just barely registers, you can pour it into the other cuvette, switch the cuvette order and see if the glass cuvettes are actually optically identical. Sets of cuvettes are, mixing between sets, they aren't!)