How to Kill Algae Without Harming Koi

During the spring ponds usually undergo a period in which algae blooms. Because the algae requires oxygen to grow, this can deplete it from the water causing your koi to suffocate and die. In order to prevent this from happening you will need to remove the algae. You can also make some additional changes to your water filtration system to insure that it doesn't grow back.

Things You'll Need

  • Skimming net
  • Water pump
  • Scrub brush
  • UV sterilizing filter
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Instructions

    • 1

      Remove as much algae as you can using a skimming net.

       

    • 2

      Use a water pump to remove about one-third of the pond's water. Replace it with fresh, clean water. Do not remove more water than this as it can cause a disturbance in the natural balance of the ecosystem that supports the pond and fish.

    • 3

      Remove the pond's water filter and flush it thoroughly with clean water. Make sure it is not clogged with algae or debris. If it is, scrub the debris free with a scrub brush.

    • 4

      Purchase a UV sterilizing filter and install it. This will simply clip in beneath the filter. Some algae are usually left behind even after you have cleaned the filter and changed the water. The purpose of the UV sterilizing filter is to kill the remaining algae. It works with the filter; as the water passes under a UV light, it will instantly kill the algae.