HI7014-25 Pool Line Free Chlorine Checker HC Reagents are high-quality reagents that are pre-measured, allowing users to achieve fast and accurate measurements with the HI7014 Free Chlorine Checker® HC. These reagents follow the DPD Method in which the reaction between chlorine and reagent causes a pink tint in the sample. By simply adding the packet of HI7014-25 reagent to the sample, the reaction will take place and the HI7014 will determine the concentration from the color that is produced. The results will be displayed in ppm (mg/L) of free chlorine. HI7014-25 Pool Line Free Chlorine Checker HC Reagents are designed to be used when measuring swimming pool, hot tub, or spa water that has an expected range of 0.00 to 2.50 ppm free chlorine.