How to Naturally Lower the Ammonia Levels in an Aquarium

High ammonia levels in an aquarium can lead to serious health issues and even death in the resident fish. Ammonia poisoning can cause lethargy, red streaking on the fins and body, a loss of appetite, and breathing problems that lead to fish taking gasping breaths at the water's surface. There are commercially available products that you can add to an aquarium to lower ammonia levels. You can also try a natural method that may take longer, but doesn't rely on chemicals.

Things You'll Need

  • Hardy fish
  • Ammonia testing kit
  • De-ionized water
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Instructions

    • 1

      Do a partial water change. This method works best for immediately lowering ammonia levels in an aquarium, and should be done at least once a week. Take at least 20 percent of the water out of the tank and replace it with fresh, deionized water. Be sure to test the new water first to make sure it is not high in ammonia.

    • 2

      Cut back on the amount you are feeding the fish. Overfeeding can cause ammonia to build up in an aquarium. Once the ammonia has become too high, stop feeding the fish entirely for one or two days. Then begin feeding again, but only one or two flakes or pellets of fish food per fish, per day. Test the water for ammonia on a daily basis until it drops to zero and stays there. You can start feeding your fish more each day, but be careful not to overfeed or you will have to do the process over.

    • 3

      Cycle the aquarium with starter fish. This should be done when you first set up the aquarium, and requires hardy starter fish to build up a biological filter to protect against ammonia. Add these starter fish as soon as you set up your tank, filter, gravel and water. Their waste and respiration will create ammonia and eventually nitrates, which will balance each other out once good bacteria is created in the filter. This process can take up to a month to complete, and some of the starter fish may die. Test for ammonia on a daily basis to see when the levels begin to drop. Once they have, you can do a water change and put new fish in the aquarium.