The best method for aquarium nitrate removal is through frequent water changes (easily done with a gravel vac). In freshwater aquariums live plants will help with nitrate removal. In saltwater aquariums protein skimmers and refugiums will help with removal. However, nitrate often persists and nitrate levels as low as 5 ppm can cause algae blooms. Nitrate can also cause stress to fish and invertebrates, and lead to diseases and reproductive failures. If nitrate persists, the aquarium nitrate removers on this page, Seachem Purigen, Seachem De-Nitrate and API Nitra-Zorb, will help to keep your nitrate levels manageable. Related Products:Aquarium ReactorsIMedia BagsINitrate Test Kits.Useful Articles: Why Do You Need Aquarium Chemical Filtration?.