This test kit has a very clear endpoint, making the test very easy to use. However, because freshwater aquaria have so little calcium (and GH) usually, the accuracy of the test is suspect. The PPS method of growing plants tells us to double the sample size to compensate. However, this fills up the test tube almost all the way. I usually measure the sample with the tube, then pour it into a glass container of some sort. I\'d also recommend you make a second sample without adding any of the #3, to compare the color. This way you can be sure you have reached an endpoint.
this came with the hagen master test kit i purchased and i just have to say that i found it to be way off the mark as far as inaccuacy. example: tested my reef tank and got over 600 ppm, didn\'t make any sense so i got a salifert test kit which gave me a much more realistic test. didn\'t work for me...sorry hagen, not this time.