Code: AQ19005Advanced Supplements for Marine Aquariums Strontium Concentrate - this solution contains the element strontium in a form easily absorbed by marine life. It safely replenishes the strontium concentration, which helps maintain optimum water quality for growth of corals and other marine organisms that deposit a calcareous skeleton. Dosage: For living reef aquariums add one capful (5ml/teaspoon) per 400 litres weekly. For coral culture systems or aquariums with a dense population of rapidly growing corals and calcareous algae, one may increase the dosage to a weekly maximum of one capful (5ml) per 200 litres. 250ml