Red Sea Coral Colours D is a trace element complex that promotes the Purple/Blue colours in corals Reef Colours D - Trace Elements PromotesColour : Blue Contains : 18 Trace elements that are depleted constantly from the water and found in coral soft tissue and skeleton Red Sea research has shown a direct relaitonship between calcium uptake and the 31 individual elements of the Reef Colour supplements. Can also be used as part of the Stage 4 - Reef Colours in the Red Sea Reef Care Program.The Reef Colours Stage 4 provides a complete solution for testing and dosing all Reef Colour Supplements based on a measured calcium uptake.Use with Reef Colours A, B, C, D and Reef Colours Pro Test Kit for accurate testing and dosingThis products is part of the new Red Sea unique Reef Care Program (RCP). The Red Sea reef care program is the result of over 5 years research from Red Sea scientists resulting in unparralleled understanding of the requirements of coral aquariums. The Red Sea Reef Care Program provides a holistic solution to maintaining a flourishing coral reef aquarium. It even allows beginners to achieve stunning sps aquariums For best results does in proportion to the dosing of Red Sea\'s Foundation A (Calcium/Strontium) supplement.