API Reef Master Test KitTo maintain and grow healthy corals, the correct balance of calcium and carbonates is essential, as are low levels of phosphate and nitrate. This kit provides highly accurate testing for each of these critical parameters: Calcium KH Phosphate Nitrate Unique, transparent dome allows clear view of contents. Kit includes computer calibrated and laminated color cards, 4 glass test tubes and holding tray. Also contains complete, step by step instruction