Tetra Test GH 723 542 (total hardness), water test for freshwater aquariums, reliably and accurately measures the total hardness, 10 ml (Misc.)
I am satisfied with the Tetra test, have the comparison made in the company where we constantly measure water hardness, it is true, the value I with the drops messe.In The company, although it is more precisely 2 places after the decimal point, but w