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. Bahamas Oolite - This oolitic sand is ideal for shallower beds, allowing denitrification in as little as 1" depth. The most friendly to bottom dwelling creatures; its fine grain size can pass easily through the gills of gobys and other sand sifting organisms. Also an excellent choice for the cultivation of seagrasses (true plants) such as Thallasia species. Gentle to sharks and rays. Grain size 0.1 - 1.0 mm.