NITRA-ZORB filtration media is scientifically proven to remove aquarium toxins. Benefits: Removes ammonia, nitrite, and nitrate Follow API Easy Care Guide and use NITRA-ZORB when: Addressing Water Solving Problems to remove ammonia, nitrite, & nitrate 1 pouch treats up to 210L for up to 2 months. NITRA-ZORB is a ready-to-use filter media pouch that can be added to your filter to remove ammonia, nitrite, and nitrate. NITRA-ZORB is made of natural and synthetic ion-exchange resins that selectively remove toxins from freshwater aquariums. NITRA-ZORB is completely phosphate-free and can be reused after recharging. We’ve proven how well NITRA-ZORB works in reducing ammonia and nitrite levels! Do you want to know how? Check out the Science Inside article here. Directions: Rinse pouch under tap water. Place pouch in path of water flow in the aquarium filter. For a new aquarium or when ammonia or nitrite is detected: recharge every 5 days for the first month, and then every 2 weeks for the second month. For an established aquarium: recharge every 2 weeks. When nitrate is detected: recharge every 5 days until nitrate is reduced to 20ppm (mg/L) or less. Replace pouch after 2 months. To recharge: Dissolve 4 tablespoons (80 g) of API® AQUARIUM SALT in 8 oz. (240 ml) of warm tap water. Soak pouch for 2 hours, then rinse lightly in tap water. When not in use, store pouch in recharging solution.