Keep your fish tank clean and healthy with the Test 6 in 1 from Tetra. This simple tester kit will ensure that your water is safe for your fish to live in. The kit will test for pH (6.4 to 8.4), GH (general hardness), KH (carbonate Hardness), Nitrite (NO2) and Nitrate (NO3). It is simple to use and will provide your fish with the healthy environment they require.