Hanna Marine Alkalinity Checker® HC - HI772 (dKH)Get accurate results for your saltwater aquarium with our simple handheld colorimeter. Our alkalinity colorimeter bridges the gap between alkalinity test kits and advanced instrumentation. Standard test kits have limited accuracy since they rely upon the human eye to match colors. Our handheld colorimeter eliminates the hassle of matching to a color chart by providing a direct saltwater alkalinity result in dKH units. Our handheld colorimeter is