Pond algae, although a necessity of every water feature is the gardeners bane.

Not long after a water garden has been installed the bloom of algae begins. Some types of algae are beneficial to the ecosystem of a pond, but too much pond algae ruins the look of a well planned water garden. If excessive algae occurs on a regular basis, installation of a biological filter or an ultraviolet water clarifier may be necessary.

Pond Algae
Algae are microscopic plants. Though small, they are very strong plants. Like all plants, algae require light, nutrients, oxygen, water and heat. The most common types of algae that will occur in back yard ponds are string, surface and green pea soup algae.

The Pros & Cons Of Pond Algae:


  • Provides shade for the fish, and protection from predators.
  • Makes a great egg shelter for fish, snails, frogs, newts, dragon flies etc.
  • Is a great food source for small fry.
  • Great source of oxygen for the fish and animals.


  • At night uses up all the oxygen, thus lowering the water quality for the other plants and fish.
  • Not very attractive, and can make it hard to locate fish and plants.
  • Decaying algae increases the amount of nutrients in the pond.

3 Types of Pond Algae:

1.) Smooth algae will grow on the liner and pots giving the water garden an aged look. This type of algae is desirable because it removes the nutrients that nourish the less desirable algae and provides 60% of the oxygen in the water. Too much surface algae can be removed with a scrub brush.

2.) Free floating, blanket weed and string algae are undesirable types of algae. This type of algae grows dark green in a long, ropy form They turn water green and murky and can choke out other plants and fish. String algae is really hard to pull out of a pond because it clings to rocks, plants and everything else and when ripped out will cause the algae spores to detach from the plants and encourage future growth. A better method to remove the string algae is to wrap it around a stick and pull it out or cut it with scissors.

The best way to prevent the infestation of algae in any water garden is the use of Barley Straw. Available in pillow or pad form, barley straw encourages bacteria to ingest the barley and give off an natural hydrogen peroxide that will kill the algae. Barley straw is safe for fish and plants.

3.) A free swimming microscopic algae is called Pea Soup Algae because of the way it makes the water cloudy, Resembling peas soup. The particles of this algae are so small that filters are unable to clear them from the water. Pea Soup Algae feeds off of phosphates which are found in tap water. The easiest way to rid yourself of Pea Soup Algae is to get a biological filter, or a UV light.

How To Control Algae In Your Pond:

  • Algae blooms occur in warm weather, so it is very important to keep your water level up during periods of warm weather when evaporation is occurring.
  • Remove filamentous algae from the surface of the water, and surrounding rocks.
  • Pond snails are a natural solutions, but they are not as effective as removing the excess algae by hand.
  • Algaecides are available but should only be used as a last resort as they kill off the algae and plant life. Algecides are only a temporary cure for the problem.
  • Read our article on Controlling Pond Algae Naturally

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