Hanna Instruments Phosphate Checker (HI774) - Ultra Low RangeThe Ultra Low Range Phosphate Checker HC (HI774) is a cost effective way to measure phosphate in marine systems, including reef tanks. Testing for phosphates is standard practice for saltwater aquariums and provides valuable insight into your reef tanks 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,