Intensify Green Coral Colour. Reef Essential® Bio-Metals™ is designed to provide ionic, complexed & chelated bioactive metals to help intensify green coral colour. The ionic & complexed are immediately bioavailable while the chelated delivers a sustained release helping to provide a consistent supply of bioactive metals to coral. This product must be used alongside our Reef Essential® Bio-Enhance™, Reef Essential® Bio-Gen™ & Reef Essential® Bio-Kalium™ supplements as together they will provide the required biomolecules, major, minor and trace colouring elements. If wanting to enhance coral bone growth & density we recommend our Aragonite Enhancers™. Recommended iron concentration = 0.1-0.3ppm.