Reef Foundation ABC+ is a blend of all of the corals foundation elements of coral skeletons: Calcium, magnesium, strontium & carbonate, with the addition of potassium, bromine and iodine in the unique ratio required by corals. All of these elements need to be available in balanced proportions for positive coral health and growth. Red Sea's Reef Foundation ABC+ is a uniquely formulated powder supplement containing all of the elements of Foundation A, B & C, plus Red Sea's Coral Colors A & B (potassium, boron, iodine & bromine) formulated in the exact ratio as found in the coral skeleton.