How to Reduce Nitrates and Alkalinity in a Koi Pond

Koi ponds add an appealing visual element to a backyard or landscape, but they need to be maintained to keep the fish healthy. Changes in weather and buildup of chemicals affect the alkalinity and the amount of nitrates a pond contains. This can be harmful to the koi if not checked and prevented. Koi ponds are expensive investments, so it is important to take care of them properly.

Things You'll Need

  • Nitrate test kit
  • Alkalinity test kit
  • Bucket
  • Fresh water
  • Net
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Instructions

    • 1

      Measure the level of nitrates in the pond using a nitrate test kit. Nitrate test kits contain a vessel to hold pond water and a pill to drop in the vessel. The pill will change the color of the water according to its concentration of nitrates, which can then be compared to a color chart. The recommended range of nitrates for a koi pond is between 0 and 200 parts per million, or ppm.

    • 2

      Test the pond water's alkalinity with an alkalinity test kit. This is similar to a nitrate test kit. Place pond water in a vessel and use pills, powder or droplets to turn the water blue. The amount of acidic reagent needed to turn the water pink determines the alkalinity. This information will be available in the test kit. Alkalinity is within an appropriate range when it is between 50 and 200 ppm.

    • 3

      Remove water from the koi pond with a bucket to reduce the amount of water in the pond. Add fresh water with the bucket to reduce the amount of nitrates and the alkalinity of the pond. Remove sludge and dead organic matter with your net to further reduce the alkalinity of the pond. Test nitrates and alkalinity again after removing and replacing some of the pond's water and dead matter.

    • 4

      Test the pond once per month to make sure that the nitrates and alkalinity stay at the correct levels.