Salifert Strontium Aquarium Test Kit. Strontium plays an important role by accelerating coral and calcareous algae growth. NSW contains approx. 7 – 9 mg/L strontium. 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. It is advisable to maintain a strontium concentration between 5 and 20 mg/L. The Salifert strontium test kit detects both ionically free and moderately complexed strontium. Salifert was the first to introduce a strontium test kit. Approx. 25 tests per kit. Measures in approx. 5 ppm increments.