Saltwater Aquarium Calcium Colorimeter - Checker HCThe saltwater calcium colorimeter fills the gap between calcium test kits and advanced instrumentation. Standard test kits have limited accuracy as they depend on the human eye to determine colors. The handheld colorimeter eliminates the trouble of matching to a color chart by providing a direct saltwater calcium result in ppm CaCO3. The portable handheld colorimeter goes where you go. Achieve your calcium results easily with simple, one button