How to Remove High Nitrates in Aquarium Water

Nitrates escalate during the first month or two of a new aquarium setup until the nitrogen cycle is complete. A fish tank filter must develop a colony of healthy bacteria before it can process waste nutrients in the water. Until the filter reaches biological maturity, high nitrates can be toxic to your fish if left untreated. This is also known as new tank syndrome. Test your aquarium water weekly with a nitrate test kit until your filter matures and carry out twice-weekly water changes to keep nitrate levels under control.

Things You'll Need

  • Nitrate test kit
  • Bucket
  • Siphon
  • Fish net
  • Beneficial bacteria solution
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Instructions

    • 1

      Test your water for high nitrates with an aquarium test kit to obtain an accurate result. You cannot see or smell nitrates in the water and the only way to measure the presence of nitrates is with a kit. If your test shows nitrate levels are dangerously high, replace 50 percent of your aquarium water immediately. If levels are high but not yet dangerous, remove approximately one-third of your tank water. Never change more than half of your aquarium water per session because you will disrupt your tank's beneficial bacteria and restart the nitrogen cycle.

    • 2

      Net out debris and leftover fish food from the substrate to prevent an abundance of excess nutrients. Waste organic material is usually the cause of high nitrates in a new tank setup because the filter's growing bacterial colony is unable to digest waste at a suitable rate during the nitrogen cycle. Eradicating the source of a chemical imbalance provides a quick fix and regular maintenance will prevent a recurrence. Siphon out debris during routine water changes to maintain healthy water and gravel.

    • 3

      Replace about 30 percent of your tank water twice a week to keep nitrate under control. You may not see levels drop to zero during the first month of a new aquarium setup, but if levels stay within the lowest range of acceptable test results, your water chemistry should be fish friendly.

    • 4

      Add a few drops of beneficial bacteria solution at each water change and when introducing new fish. This is a clear liquid containing a live culture that populates your tank with essential bacteria to enhance the biological properties of your tank filter and balance chemical levels. A healthy bacterial colony is necessary for healthy water chemistry and a nitrate-free ecosystem in your aquarium.