API® NITRA-ZORB filtration media is a ready-to-use pouch that can be added to your filter to remove ammonia, nitrite, and nitrate. NITRA-ZORB filtration media is made of natural and synthetic ion-exchange resins that selectively remove toxins from freshwater aquariums. NITRA-ZORB filtration media is completely phosphate-free and can be reused after recharging. 1 pack - size 6. >>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. R eplace 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.