Hanna Colorimetric Checkers for Alk and Ca? F! yes!!

[Ron99]

The tests are not electronic. these are small portable colorimeters probably each tuned to the narrow wavelengths of the particular test they do. So it is just a replacement for our test tube tests. but in the case of things like phosphate, nitrates etc. wher you are trying to match a colour these are most likely more accurate as they don't depend on the colour temperature of the lighting you are doing the test under and a judgement call of what you think the colour is etc.

For stuff like Alk and Ca and Mg that are titration tests with a distinct colour change the advantage might lie in greater precision (which we'll know once they release more information about the checkers) and convenience.