Only CaribSea's Arag-Alive! Live Sands contains not just the broad spectrum of natural marine bacteria found in the ocean, but additional specially selected strains of marine bacteria as well. Arag-Alive! compresses new tank cycle time and suppresses the initial ammonia spike. Arag-Alive! creates a natural biological balance, and makes cycling a new aquarium faster and safer. Live rocks and most invertebrates can be added immediately. Gradually introduce fish within the first 3 weeks, and do not exceed one inch of fish per 5 gallons during this time. Special Grade Reef Sand - Grain Size 1.0 - 2.0 mm. This coarse sand is 100% aragonite and has excellent diffusive properties. A very versatile product, use in a deep or shallow beds. A significant denitrator when utilized in deeper beds or plenum systems. Royal Item Number: ACS01790