Preis Mineral Salt is a salt for the preparation of mineral-rich sea water for your aquarium. Preis Mineral Salt contains a mixture of all of the compounds present in natural sea water, such as minerals, trace elements and vitamins which are vital for the growth and thriving of invertebrates and coral. Preis Mineral Salt should be added to osmosis water or soft tap water to make mineral-rich water for the replacement of evaporated aquarium water or for water changes. This formula is free of sodium chloride (common salt) and is ideal for the manufacture of alkaline freshwater, such as those found in the Malawi and Tanganyika lakes. Please refer to the product guidelines for the amounts to use.