Seachem Reef Plus is a full spectrum reef supplement containing trace elements, vitamins, and amino acids demonstrated to have a positive impact on the growth of corals and other desirable reef creatures. Reef Plus is formulated to provide nutrients available from natural tropical reef waters. Contains vitamin B12, vitamin C, thiamine, inositol, choline, iodide, and other essential constituents. Reef Plus is nitrate/phosphate free. Unlike many manufactures whose supplements contain only vitamins and trace minerals, Seachem Reef Plus contains necessary amino acids in addition to a full complement of trace minerals and high amounts of vitamin C and B complex vitamins. It is so concentrated that it can be effectively used as a food soak for frozen fish foods. 500ml.