The Kent Marine Reef Starter Kit provides quality products for the three most important additives for marine invertebrate keeping: calcium, strontium, and iodine.Liquid Calcium. Provides bio-available calcium for healthier, more beautiful corals, hard tube worms, snails, other invertebrates, as well as coralline and other calcareous algae. Contains no gluconates, lactates, or other sugars.Strontium & Molybdenum. Provides bio-available strontium and molybdenum. Corals will open more and stay attached to their skeletons better with regular use. Contains no gluconates, other sugars, EDTA, or other organics to raise system DOC. Will not promote undesirable algae growth.Iodine. Provides bio-available iodine to reef inhabitants. Although present in salt mixes, iodine is rapidly used up in the system, and removed by protein skimming and ozone. Algae also use iodine. Concentrated Iodine Supplement replaces iodine needed for proper growth and health of invertebrates and algae. Contains a safe, stabilized form of iodine which will not destroy system bacteria.