Planktonic Algae


Planktonic Algae blooms cause the water to turn a pea-soup green color. Not only does planktonic algae ruin the aesthetic look of your pond, it can cause a great danger to fish when trying to treat it. What happens is when the planktonic algae dies off rapidly, from either weather change or treating the water with an algaecide, it will deplete oxygen from the water, possibly causing a fish kill if the oxygen depletion is great enough. Although it is not a 100% guarantee to prevent a fish kill, having an aeration system will reduce the possible risk of one.

Mechanical Control

Using Pond Dye will help to limit sunlight into the pond for algae to complete photosynthesis.

Reducing the overall nutrient load in your pond will help to keep algae blooms to a minimum. Use PondClear or MuckAway to reduce overall nutrients.

Chemical Control

There are several chemical options to control planktonic algae. They should be applied when the algae is actively growing. Applications should begin when algae first appears as long as your water temperatures are above 60°F. Unless steps are taken to reduce the overall nutrient load, multiple applications may be needed for full season control.

Chemical Application Best Practices

Anytime you use chemicals treat algae or weeds, please keep in mind the following:

  • Treat your pond in sections. Treat only half the pond's surface at a time. During hot weather or when treating heavy growth, it is important to treat no more than ¼ of your pond at a time and wait the full 14 days before re-applying. This helps lower the risk of fish loss during hot weather or when treating heavy growth.
  • Once the weeds have browned & died, use a rake to remove as much dead material as possible. This prevents an accumulation of dead plant material and muck.
  • Take a proactive approach to pond management. Use PondClear, MuckAway and Pond Dye to keep your pond looking great. For more information, see our article on the Airmax® Ecosystem

Ask an Expert

If you are unable to identify your pond weed(s) using our Weed ID Guide, follow this article to email us a photo.

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