Blend of premium activated carbon and ammonia-neutralizing crystals for clean, healthy, sparkling aquarium water. Works faster, longer, and better than all the rest--outperforms other blends by as much as four to one. Special formulation (with 25% more carbon) effectively purifies aquarium water--ridding it of dissolved organic waste and odors as it neutralizes toxic ammonia and chloramines. Perfect for controlling toxic ammonia buildup in new aquariums during the crucial break-in period.