Common Types of Algae

Often found in ponds and aquariums, algae are an indication of good water quality when present in small quantities. They represent a large group of organisms that require light, water and nutrients to grow. Although algae look like plants, they do not have the roots, stems or reproductive structures found in plants. Most algae are microscopic. Others, such as marine seaweed, are quite large and can exceed 150 feet in length.

  1. Green Water Algae

    • Green water alga is an organism that floats in the water, giving your pond or aquarium an unpleasant cloudy green appearance. This type of algae does not affect the fish or plant life in your aquarium. They provide beneficial services to your pond or aquarium, helping to clean the water and providing an alternative food source for tiny fish that feed on plant life in the water. An overabundance of green algae in your aquarium indicates a nutrient imbalance in the water. Check with your local gardening store to obtain help in dealing with this problem.

    Black Brush Algae

    • Black brush, or beard, alga grows on gravel or covers the leaves of slow-growing plants in an aquarium. It resembles small bunches of black hair or a piece of black carpet. The strands of this alga grow to a length of about one-half of an inch. They are one of the most difficult algae to get rid of. If black brush algae are growing on the leaves of your plants or on the glass in your aquarium, you might have to remove the entire algae-covered leaves and introduce the only known fish that consumes this type of algae. The siamensis fish does an effective job of removing black brush algae from the leaves of the plants and from the glass of your aquarium.

    Seaweed

    • Seaweed is not really a weed but rather a large form of algae that grows in ocean waters around the world. They range in size from microscopic plants called phytoplankton to the familiar giant seaweeds. Seaweed comes in brown, red and green. Many products are derived from the various kinds of marine algae. Carrageenans, used for stabilizing and gelling foods and cosmetics, are harvested from the red seaweed. Alginates come from the cell walls of the brown seaweed. They are used to provide the smooth texture in ice cream and to prevent ice crystals from forming in the ice cream. Pigment obtained from green seaweed is used as in yellow-orange food colorings.

    Blue-Green Algae

    • Although most algae are multicelled, blue-green, or slime, alga is the exception. It belongs to the class of algae called cyanobacteria and is the only single-celled algae. It is found in colonies in lakes and other natural bodies of water and also occurs in ponds and aquariums. Blue-green algae are exceptionally difficult to get rid of. If this alga appears in your aquarium, the only way to remove it is to dump out all the water and completely clean the aquarium. Blue-green algae are fast-growing, unsightly and an indicator that your aquarium water has high levels of phosphates and nitrates. Changing the water frequently and using LED lighting may help to control the growth of this type of algae.