Characteristics: Reduces Consumption of CO2. Perfect for all types of Calcium Reactors. Safe for Reefs. 100% All Natural - From The Ocean To You. No Phosphates or Silicates. Grain Size approx. 4-6mm. Recommended Use: Nature's Ocean Premium Aragonite Reactor Media is ready to use right from the container. Just add reactor media to approximately three quarters full add seawater and run system.