How to Get Green Algae Out of a Fish Pond

Algae control is an essential part of maintaining an outdoor fish pond, an environment commonly used to house koi. Because they are outside, these ponds are constantly exposed to sunlight and stray organic nutrients, both of which promote algal growth. One type of algae that's particularly annoying is green algae, which is composed of tiny, microscopic phytoplanktons that give the water an ugly, green tint. There are many chemical solutions sold in stores to help eliminate this problem, commonly called algaecides, but they can be potentially harmful to your fish if used improperly. Luckily, there's another, much easier and natural way to both eliminate and prevent green algae.

Things You'll Need

  • Hose
  • Dechlorinator
  • Water lilies
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Instructions

    • 1

      Using the hose, siphon about one-third of the water from your pond.

    • 2

      Refill the pond, making sure that the fresh water is about the same temperature of the water already in the pond.

    • 3

      Add the appropriate amount of dechlorinator. This amount should be specified on the product's packaging and is dependent on the amount of water you replaced.

    • 4

      Scatter water lilies across your pond until they cover about two-thrids of the surface. They will shield much light from reaching the water and also absorb many nutrients the algae would otherwise use to grow and spread. The green algae should gradually vanish within about two weeks.