The LaMotte ColorQ Pool 4 measures DPD Total Chlorine (0 to 10.00 ppm). In additional, the unit can also measure DPD Free Chlorine (0 to 10.00 ppm), Bromine (0 to 22.0 ppm), pH (6.5 to 8.5 pH), Cyanuric Acid (0 to 125 ppm), Total Alkalinity (0 to 250 ppm), and Calcium Hardness (0 to 700 ppm) with optional reagents sold separately. The compact photometer is easy to use and utilizes economical liquid reagents, good for 144 tests per reagent type.