How to Decrease Nitrates in Your Aquarium

Water chemistry is unstable during the first few weeks of a new aquarium setup, as nitrate levels rise as part of the nitrogen cycle. A tank filter must develop a healthy bacterial colony to process excess nutrients in the water, and until the filter reaches full biological efficiency, nitrates can escalate to dangerous levels and kill your fish. It is important to monitor your aquarium with a nitrate test kit until your filter matures. This may take up to two months, so carry out regular partial water changes to decrease nitrates and prevent further problems.

Things You'll Need

  • Nitrate test kit
  • Bucket
  • Siphon
  • Fish net (optional)
  • Water dechlorinator
  • Floating thermometer
  • Beneficial bacteria solution
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Instructions

    • 1

      Test your tank for signs of nitrate with an aquarium water test kit to confirm an accurate diagnosis. Siphon out approximately 30 percent of your aquarium water to remove as much nitrate-containing water as possible, without disrupting the overall ecosystem in your tank. Large, drastic water changes do more harm than good and cause stress to your fish, so never change more than 30 to 50 percent in one session. If your test indicates nitrates are dangerously high, remove half of your aquarium water immediately as an emergency measure.

    • 2

      Siphon or net out debris and uneaten fish food from the gravel to eradicate excess waste. An abundance of nutrients causes nitrate levels to escalate during the nitrogen cycle, and decomposing organic material is often the cause of "new tank" syndrome. Eliminating the source of a nitrate problem provides a quick solution and prevents a recurrence, so siphon out debris with water during subsequent partial water changes to maintain healthy substrate.

    • 3

      Mix tap water with dechlorinator in a bucket, according to the manufacturer's dosage instructions, and stir thoroughly. Place a floating thermometer in the bucket, and adjust the water temperature by adding warm or cold water until it is the same as your aquarium's temperature. Pour the prepared water into your tank, and repeat the process until your aquarium is back to its normal water level.

    • 4

      Replace about a third of your tank water every three or four days to keep nitrate at a minimum. Levels might not drop to zero during the first three weeks of a new tank setup, but if nitrate remains within the acceptable range of test results, there is no cause for concern. Never change all of your tank water in one session, because you will disrupt the nitrogen cycle, setting it back to day one.

    • 5

      Shorten the nitrogen cycle with a beneficial bacteria solution. This populates your tank with the required good bacteria and kick-starts the biological process in your tank filter, balancing ammonia, nitrite and nitrate. Top-up your bacteria when adding new fish and as a routine booster with every water change. A strong bacterial colony helps to maintain healthy water chemistry and a stable nitrate-free environment for your fish.