Nope, I do not use these.
They are non specific for alkalinity, so it's not all carbonate hardness in the alkalinity of the sample, nor does it account for peat/tannins/humic acids etc.

They have the same issues as a pH measure.

Now you can do a two part reference approach.
Use a known KH and an unknown KH/inteference sample that are both in equilibrium with air after 48 hours.

Measure them, then subtract the difference.

Say the known KH has a pH of 7.5
The unknown has a pH of 7.2

You use the pH/KH chart, but remove/subtract 0.3 pH units for the actual measurement for CO2.

I'm not sure why more folks have not done this, I did this method to account for peat and other issues some 10 years ago and posted it on the APD.

It's not perfect, but drop checkers are not either.

The other issues: KH variability through time, peat and other acids influence through time all change, as does the tap's KH.

Folks often just measure pH often...........and rarely test the KH in the tap water, they assume it's stable, generally it moves around and can a great deal depending on the tap water supply.

Note:
While the subtraction method works fairly well, there may not be a linear relationship. So while at a the pH's of 7.5 and 7.2 work okay, when you add CO2 and drop the pH down at 6.4 and subtract 0.3 from there, it may not be the same.

To address this, you can take the known KH reference sample and add CO2 as well as the sample from the tank water.

Lower the pH using CO2 for both samples and see if the difference is the same.
I think it is for most part.

This is a good method for folks using pH meters.


Regards,
Tom Barr