How to Lower the Nitrogen Level in an Aquarium

One of the toughest challenges facing new aquarium hobbyists is the monitoring and maintaining of water quality. Fish waste, rotting plants and uneaten food are all sources of deadly ammonia in an aquarium. In a properly "cycled" aquarium, beneficial bacteria convert ammonia into nitrite (still deadly) and then into nitrate (less harmful) in a process called the nitrogen cycle. But even in an established aquarium, nitrite and nitrate levels can spike. Luckily, there are steps you can take to quickly lower nitrogen levels in a cycled tank.

Things You'll Need

  • Water test kit
  • Dechorinating solution
  • Aquarium siphon
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Instructions

    • 1

      Monitor ammonia, nitrite and nitrate levels on a daily basis using a commercial test kit. In a properly cycled tank, the ammonia and nitrite levels should be zero. Nitrate levels should be above zero but shouldn't be allowed to stray into the mid- to high range.

    • 2

      Perform a partial water change in your aquarium if ammonia or nitrite levels are greater than zero or nitrate readings are in the mid-range to high. Remove one-third to one-half the water and replace it with dechorinated water. Adjust the water temperature so that it is similar to the water already in the tank. Test the levels again in an hour.

    • 3

      Remove rotting food, plant debris or dead fish using a siphon. For larger items you may need to use a net or aquarium tongs.

    • 4

      Change the filter media in your filters and add additional filtration to the tank if high levels persist. Inadequate filtration can cause nitrogen levels to rise quickly.

    • 5

      Move some of your fish to another tank if the previous steps fail. An overloaded tank can cause nitrogen levels to spike.