How to Reduce Nitrites in an Aquarium

Nitrites are a highly toxic byproduct of ammonia in aquariums. Bacteria in the tank will take ammonia and convert it to nitrite over time. Too much nitrite will almost inevitably kill your fish, with the ideal level being zero ppm (parts per million). Examine your aquarium water with a testing kit to determine the nitrite level, and if it's too high, you can take several steps to reduce it and keep it low.

Things You'll Need

  • Gravel vacuum
  • Bucket
  • Liquid dechlorinator
  • Live plants
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Instructions

  1. Removal of Nitrites

    • 1

      Vacuum out the aquarium's gravel with a gravel vac, which siphons out the water and any organic particles but does not suck up the rocks. This will remove any rotting organic matter, like uneaten food, that decomposes into harmful ammonia. Place a bucket at the other end of the gravel vacuum's hose to catch the dirty water. Only vacuum until approximately one quarter of the water has been removed.

    • 2

      Replace the water removed from vacuuming the gravel with clean water. Add liquid dechlorinator to the tank when you do. This dechlorinator removes chlorine and other harmful chemicals that could be present in tap water. The proper dosage will be specific to the manufacturer and will be listed on the packaging.

    • 3

      Put numerous live plants in the tank. Live plants suck up ammonium, which becomes ammonia and eventually nitrites, and will go a long way toward the long-term reduction of the poisonous chemicals. Some plants that are easy to care for include anacharis and sword plants.

    General Prevention

    • 4

      Do not overfeed your fish. Fish food is made up of organic matter, and any uneaten food will sink to the bottom and dissolve into ammonia, which is then in turn converted into nitrites. Only feed your fish as much as they can consume in a few minutes and no more.

    • 5

      Change the water regularly. Swap out about one quarter of the water once per week. This will not only keep ammonia and nitrite levels down but will keep the water clean and clear.

    • 6

      Change or replace the filter cartridges regularly. The cartridges collect the fish waste and other debris and over time could be rendered ineffective if they are too dirty. Rinse slightly used cartridges under a faucet and replace cartridges that are more than a month old.