The API Freshwater Master Test Kit tests tap and aquarium water for five essential water parameters including all tests required for testing the nitrogen cycle. The kit includes computer-calibrated and laminated color cards, 4 glass test tubes and holding tray. Also contains complete, step-by-step instruction booklet, including information on how to correct unsafe water conditions. The API Freshwater Master Kit is compact and easy to store, highly accurate and economical. Contains 800 tests.