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Filamentous Algae


Filamentous Algae will often form mats that float on the surface of the pond resembling wet wool. Most pond owners commonly refer to this type of algae as "pond scum", but can often be called string algae, or floating algae. This is a very common type of algae found in ponds, but if left untreated can cover the entire surface of your pond.

Mechanical Control

Filamentous Algae can be removed from the pond by raking. 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 filamentous 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°. Over time, the algae will begin to brown and die. Once it is completely dead, use a rake to remove dead algae away to prevent an accumulation of dead algae and muck. 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, if the weather is hot, only treat 1/4-1/3 of your pond. Wait 10-14 days between treatments.
  • Once the weeds have browned, use a rake to remove as much dead material as possible. This prevents an accumulation of dead plant material and muck.
  • Treat your pond with the proactive approach to pond management. Use PondClear™, MuckAway™ and Pond Dye to keep your pond looking great.