How to Lower Nitrate in a Fish Aquarium

In saltwater aquariums, nitrates get into the water mainly through fish waste and deteriorating algae. If your nitrate levels are on the rise, that generally indicates a decrease in overall water quality. You can lower nitrates and then keep them low in your salt water aquarium in a variety of ways.

Things You'll Need

  • Fish that eat algae
  • Paper towels
  • Nitrate filter
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Instructions

    • 1

      Clean out the algae in your aquarium. If the algae in your aquarium is growing over the walls and making the water murky, the odds are good that you have just spotted your nitrate problem. Wipe down the walls of the aquarium with a paper towel. Be sure that your hands are clean but completely free of soap before you do this.

    • 2

      Change out about 25 percent of the water each week until the nitrate levels fall and stabilize. If you change any more water than this, you run the risk of shocking your fish. Once the nitrate levels are where you want them, you can start changing the water every two weeks or even once a month.

    • 3

      Install a nitrate filter in your tank. These filters generally fit in any filtering system. They are made of zeolite and will help you bring about a quick change to nitrate levels. However, they are not a permanent solution without making other changes to the state of your aquarium.

    • 4

      Bring in some algae-eaters. Fish like tangs and gobies control algae and other waste in the tank. They are fairly hardy and tend to get along well with other fish.

    • 5

      Feed your fish less. If you are just tipping up the fish food and letting it pour in, you are probably the source of the nitrate problem. Look at the prescribed amount of fish food recommended by the fish food manufacturer. Then apply it to the number of fish in your tank. Do not give your fish any more than the recommended amount.