The Salifert test kit measures in steps of 5 mg/L and has an accuracy of 10 mg/L. The color change is precise, detecting small but significant fluctuations in the concentration of calcium. The test is not affected by magnesium.Sufficient for 50-100 tests.Can be used for marine water, freshwater and garden pond waterWarning!Ca-1 reagent contains sodium hydroxide and is strongly irritating to skin and eyes. In case of contact with skin wash with plenty of water. In case of contact with the eyes wash with plenty water and consult a physician immediately.Not for consumption. Keep out of reach of children. If swallowed contact a physician immediately.