Oliver Knott American Cichlid Aquarium Salt contains essential electrolytes and is mineral rich in calcium, magnesium and iron which can help improve water quality by removing ions and replacing lost trace elements during water changes. Harvested through advanced solar evaporation techniques from the waters of the world famous Australian Great Barrier Reef, this aquarium salt is like no other in the world. Directions South American 15g (1 2/3 teaspoon) Central American 7.5g (5/6 teaspoon)* for each 550L (150 US gallons). Use when setting up an aquarium and when making water changes. It is best practice to first dissolve the salt in a small amount of freshwater before use. Only use salt during a water change, not when replacing evaporated water. *If unsure of species, use Central American dose.