salinity is a blend of salts specifically formulated for the reef aquarium that contains all essential major, minor, and trace components found in natural reef waters, but contains no toxic or non-essential components. Additionally, salinity is the most concentrated salt blend on the market. With a hydration level of <0.5% salinity will yield a greater volume of prepared saltwater at a salinity of 35‰ per unit of weight than any other salt mix currently on the market. salinity is identical to the distribution of anions and cations found in Natural Sea Water (NSW). We have compiled data from all the oceans and seas on the Earth, and have targeted the midpoint of the range for each element. We guarantee to be within ± 5% of the midpoint.