Your Choice Aquatics – Bio Plate Filter MediaHigh-Performance Bio Filter Media- Increased Beneficial Bacteria Colonies- Helped Reduced Phosphates and Nitrates- Large Surface Growing Bacteria, Approximately 10,500sqft Per Plate- Safe For Reef, Saltwater, Aquarium, and PondHow To Use- Rinse The Bio-Plate Carefully With Freshwater- Place the Bio-Plate In An High Oxygenate Area or Strong Flow- Bio-Plate Can Be Use As A Frag Plate To Grow Corals4x4x1″ each plate x 2pcs per box