Strontium plays an important role by accelerating coral and calcareous algae growth. Since the growth of corals and calcareous algae goes hand in hand with strontium and calcium depletion, depletion of calcium usually means depletion of strontium as well. Strontium measurement is a necessity but is unfortunately a relatively difficult test. Perhaps in forthcoming years this will change when newer and easier methods for strontium measurement will become available. It therefore is a test, which many hobbyists will not conduct frequent enough. For that particular reason strontium additives should be designed in such a way that a too low or a too high strontium concentration is avoided. With the Salifert Natural-Strontium additive we have reached this aim. When used in combination with our Coral Calcium additive according to the instructions then the need for strontium measurement is greatly reduced and would have to be performed only once every few months. The Salifert strontium test kit detects both ionically free and moderately complexed strontium. Salifert was the first to introduce a strontium test kit.