A must have! By Phil on 8/8/2017
Phil would recommend this product to a friend
You must have this in order to continually check the accuracy of your meter in order to eliminate any doubts about your the test on your tank water. Mine showed it was 5ppm lower than rated, so I adjust my final readings on my tank water sample.
Worked within its range! By Steve on 12/8/2016
Steve would recommend this product to a friend
It tested as it was advertised. There is a expiration date on the vials, which I didn't expect but makes sense if the standard has to be color specific. They store in a black plastic case that fits the box they come in so they can be protected from light and not fade I guess. The alkalinity and calcium are the same besides there different colors.
Excellent By Donald on 9/18/2016
Donald would recommend this product to a friend
Easy to use.