Fluval® Lab Series Nitrate Remover is a high-capacity, laboratory-developed ion exchange resin that is safe for fish, plants and invertebrates. Developed from a pure high-grade string base anion exchange resin, Nitrate Remover rapidly and selectively removes nitrate and eliminates toxic nitrite in a matter of hours, resulting in a healthy environment for your fish. It removes up to 25 mg/L (ppm) of toxic nitrate per 189 litres (50 U.S. gal.). It does not contain phosphate, will not affect pH or Hardness, and can be recharged several times. For freshwater use only. 150 g (5.29 oz).