The HI717-25 are high-quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Phosphate High-Range Checker® HC. These reagents follow the Amino Acid Method in which the reaction between phosphorus and reagents causes a blue tint in the sample. By simply adding 10 drops of the first reagent to the sample, followed by the packet of the HI717-25 reagent set, the reaction will take place and the HI717 will determine the concentration from the color that is produced. The results will be displayed in ppm (mg/L) of phosphate. These reagents are designed to be used with samples that have an expected range of 0.0 to 30.0 ppm (mg/L) phosphate.