Quickly measure and modify the six aquarium levels that are most important to the health of your freshwater fish with the API Freshwater Master Test Kit. To stay healthy and thrive, fish need properly balanced levels of ammonia, pH, high range pH, nitrite and nitrate. These levels can change rapidly and create harmful conditions when fish waste, uneaten food or other organic matter accumulate, or when untreated water is added. If left uncorrected, all of these can be harmful or even fatal to fish, with consequences such as reduction of oxygen, increase in stress and higher risk of disease. This kit measures these six parameters with scientific accuracy and provides professional results. It comes with four glass test tubes, 7 test bottles, holding tray, test tube rack and computer calibrated, laminated color card. Just fill the test tubes, add the test drops and compare results to the color card. Then follow the recommendations on the card if action is required.