Using Tetra Test 6 in 1 test strips is a quick and easy method of measuring the parameters and quality of the water in freshwater aquariums and ponds. These strips test for Permanent Hardness (pH), Carbonate Hardness (kH), General Hardness (gH), Nitrite (NO2), Nitrate (NO3), and Chlorine (Cl2). Available in packs of 10 and 25 strips (x6 tests)