Reef Colors C Supplement is part of the complete range of complementary major, minor, and trace element complexes which together provide the needs of corals. Reef Colors C Supplement contains Iron, Manganese and other trace elements that are associated with many biological processes, one of them being the production of the green/yellow pigments in the soft tissue of corals. To ensure coral health, the ppm level of these elements must be maintained within a narrow band and therefore should only be dosed according to a measured requirement of the aquarium. For optimal results, dose according to a measured uptake of Iron using Red Sea's Iron Pro test kit.