Our Calcium Chloride is a highly soluble form of inorganic calcium which makes it ideal for rapidly raising dissolved calcium levels in marine aquaria. It is a very pure anhydrous grade free of phosphate and nitrates. The highly soluble property allows the aquarist to rapidly adjust calcium concentrations to desired levels. The aquarist should be aware that Calcium Chloride does not add bicarbonate and carbonate ions to the system. Since most calcifying organisms require these ions in addition to calcium ions, the aquarist should monitor alkalinity frequently when using Calcium Chloride, and make the proper adjustments with a buffer additive. Calcium Chloride can directly reduce alkalinity by elevating the calcium ion concentration to excessively high levels, and thereby initiate the precipitation of calcium carbonate from the water. This may or may not be visibly detectable, depending on the magnitude of precipitation. Excessive use of Calcium Chloride may disrupt the balance of ions in a marine system by the continued addition of chloride ions. We recommend B-Ionic Calcium Buffer or Calcium Hydroxide as better long-term calcium and alkalinity supplements, but Calcium Chloride can be very useful in restoring low calcium ion levels in systems with adequate to high alkalinity levels.