Tropic Marin is one of the most well-respected and used sea salt mixes in Europe and is used by many zoos, public aquariums, research facilities, and universities around the world. It has been around for 50 years. This salt mix was the first in the Tropic Marin line and has alkalinity 9-10dKH, Calcium: 370-450 ppm, and Magnesium: 1250-1300 ppm. Made with all pharmaceutical-grade raw materials, it has zero nitrates, phosphates, and silicates. It always dissolves cleanly and crystal clear with no residue and is produced in our lab under the strictest batch controls.