Marine Phosphate Ultra Low Range Colorimeter - Checker HCThe HI774 Ultra Low Range Phosphate Checker HC (Handheld Colorimeter) is a cost effective way to measure phosphate in reef tanks. Testing for phosphates is standard practice for reef aquariums and provides valuable insight into your tank's water chemistry to help ensure long term coral health. Phosphates are one of the many forms of phosphorus compounds found in marine waters. Excessive phosphate levels can prevent calcification, skeletal formation,