Measures the most important aquarium levels quickly and accurately. A complete kit for testing aquarium water. Tests water four ways to protect fish and invertebrates from dangerous water conditions. Kits includes tests for: pH (Freshwater Kit only), High Range pH (Both Freshwater and Marine Kit), Ammonia, Nitrite, Nitrate, plus four test tubes, holding tray and test tube rack. Fast, easy and accurate. Benefits:- Tests pH (Freshwater Kit only), High Range pH (both kits), Ammonia, Nitrite & Nitrate- Scientifically accurate for professional results Use the API Master Test Kit: During Regular Care When addressing Water Problem Solving issues Taking a few minutes each week to maintain and monitor aquarium conditions is the key to a healthy aquarium. The Master Test Kit tests the parameters that affect the health of fish: pH, Ammonia, Nitrite and Nitrate. The kit is highly accurate and economical, and includes a computer calibrated, laminated color card, 4 test tubes and holding tray. The kit comes with a complete, step-by-step instruction booklet, including information on how to correct unsafe water conditions.