Water test kit for reliable and accurate determination of four essential water parameters. The Tetra Test water test kit measures the four most important water values: total hardness GH, carbonate hardness KH, pH value (freshwater), and nitrite content NO2. In addition to the test reagents, the kit includes four cuvettes, color charts, and a dosing syringe. It provides reliable and accurate measurement results as well as a wide range. After measuring the pH and KH values, the CO2 content of the water can be read from the CO2 calculation table. The instructions contain many valuable pieces of information on aquarium water. All tests included in the water test kit are available as refill packs. The kit is an ideal gift for beginners.