API Ammo-Carb Activated Filter Carbon & Ammonia RemoverAmmo-Carb is a unique blend of activated carbon and ammonia-removing resin. The activated carbon removes toxic organic waste, colors, and foul odors. The ammonia-removing resin removes ammonia produced from decaying fish waste and uneaten fish food and the ammonia in chloramine. Phosphate free. For freshwater aquariums. Protect your fish-use Ammo-Carb. It's like a double filtration system in your aquarium. Use 1/2 cup of Ammo-Carb for each ten gallons of aquarium water-Ammo-Carb can be used in all filter cartridges. Replace Ammo-Carb every 30 days-or sooner if unusual odor or color is detected.