The HI755 Checker HC (Handheld Colorimeter) provides a simple, accurate and cost-effective way to measure alkalinity. Crucial in marine environments, alkalinity provides both the carbonate ion required for calcium carbonate skeletal regeneration of coral reefs, as well as a pH buffer against large changes in acidity. Designed as a more accurate alternative to chemical test kits, the HI755 provides quick, accurate results in a few easy steps.