How to Remove String Algae Without Chemicals

String algae is also referred to as pond scum, hair algae, or blanket weed. It is a common problem in ponds and aquariums because it thrives in warm, nutrient-rich water with plenty of light. Algae is usually introduced by new plants, so any new additions should be properly cleaned. String algae is not harmful, but you probably wish to remove it for aesthetic reasons. Once string algae has a foothold, it is very difficult to remove. However, using chemicals to kill algae is not a good idea, as this can harm the fragile ecosystem of a pond or aquarium.

Things You'll Need

  • Toothbrush or rake
  • Shade plants
  • Floating plants
  • Submerged plants
  • Barley straw or extract
Show More

Instructions

    • 1

      Remove the filaments of algae manually by twirling them around a toothbrush, stick, toilet brush, or rake. Physical removal alone will not prevent algae growth, but it does help to control the spread and make it more manageable.

    • 2

      Create shade by building a fence or pergola and planting tall plants such as cattails near the edge of the pond. Floating plants such as water lilies can also reduce the availability of light that is necessary for algae to grow. Inert vegetable dyes can be added to pond water to filter out the sun's rays. They will tint the color of the water, but they are natural and safe for plants and fish. Keep your aquarium out of direct sunlight and do not leave the lights on for more than 12 hours a day.

    • 3

      Introduce more submerged plants to compete with the algae for light and nutrients. Make sure new plants have been cleaned to avoid adding more algae or other pests to your tank or pond. Some fish, such as grass carp, actually eat algae, but they will probably eat other available plant life as well so they may be more trouble than they are worth.

    • 4

      Add bundles of barley straw to outdoor ponds. Although barley does not kill algae, it efficiently suppresses algae growth as the straw breaks down. It may take weeks for the barley to start releasing enough enzymes, so it is important to keep up with manual removal of the algae. Barley extract is also available to speed up this natural process and is suitable for use in some fish tanks.

    • 5

      Avoid overfeeding fish in order to reduce the amount of nutrients available for algae. Frequently change the water in your fish tank and thoroughly clean rocks and aquarium equipment that may be harboring algae cells and the organic waste materials that are necessary for their survival.