How to Remove Nitrates From an Aquarium

New fish tank setups must go through the nitrogen cycle before the water is free from toxins and safe for fish. Ammonia, nitrite and nitrate build up over the first three weeks until good bacteria colonize the filter and gravel. This is called new tank syndrome. These chemicals are toxic and kill your fish if left untreated, so monitor aquarium water with a test kit and change a third of the water every three or four days as a precautionary measure. If nitrate is already elevated, replace 50 percent of the water immediately.

Things You'll Need

  • Ammonia test kit
  • Nitrite test kit
  • Nitrate test kit
  • Beneficial bacteria solution
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Instructions

    • 1

      Check your aquarium for ammonia and prevent a buildup of nitrate. Nitrate appears after high readings of ammonia and nitrite, so eliminate ammonia in the early stages of the nitrogen cycle and stop nitrate developing. Replace a third of the water immediately if ammonia is high, and continue to check your water chemistry daily with a test kit.

    • 2

      Test your water for nitrite and nitrate with the relevant kits. Easy-to-read, color-coded charts enable you to interpret results without any scientific knowledge. Match your result to the manufacturer's chart, and if your result is in the high color range, indicating dangerous nitrate levels, replace half of your aquarium water immediately.

    • 3

      Replace 20 to 30 percent of the water every three or four days to keep nitrate at an acceptable level. The nitrogen cycle starts over if you empty your fish tank and refill it with fresh tap water so carry out small, frequent water changes. When cleaning tank contents, wash the filter and substrate in a bucket of old aquarium water to maintain beneficial bacteria colonies. Clean tap water destroys good bacteria, disrupting the nitrogen cycle.

    • 4

      Boost your filter with a dose of beneficial bacteria solution to shorten the nitrogen cycle and balance ammonia, nitrite and nitrate. Add the bacteria with each water change and when introducing new fish. A powerful bacterial colony keeps your tank filter working efficiently, maintaining healthy water chemistry and a stable environment for your fish.