Increase the overall filtration power of your tank by adding Genesis Rock to your system. – Designed For Fresh or Saltwater Aquariums – 23,000 Additional Square Feet of Bacterial Space For Each Rock -4 Rocks Included in Set – Reduces Phosphates and other dissolved organic compounds. – Increased Beneficial Bacteria Colonies – Zero Leach Technology – 100% Fired Ceramics What is Genesis Rock? Genesis Rock is a 100% Ceramic Compound fired at 600 degrees that will last in your tank for years. Providing over 23,000 square feet of space per black for beneficial aquarium bacteria to form, these blocks providing a tremendous amount of filtration power and significantly reduce phosphates, nitrates, and other dissolved organic compounds. The Genesis Rock can be used in fresh or saltwater aquariums and can be used under your sand or rock substrate, in your refugium, or simply hidden in your aquascape.