E.S.V. Strontium Chloride Solution is a very pure and concentrated form of strontium, free of phosphates and nitrates. The aquarist should be aware that Strontium Chloride does not add bicarbonate and carbonate ions to the system. Since most calcifying organisms require these ions in addition to strontium ions, the aquarist should monitor alkalinity frequently when using Strontium Chloride and make the proper adjustments with a buffer additive.