How to Stop Algae in Garden Ponds


Algae is not only unsightly, but it can also grow until it suffocates your fish and plants. Just like other plants, algae needs light, nutrients and water to grow. So to control algae growth, you'll need to control these factors to stop algae growth. There are many natural ways to control algae, as well as chemical and filtration methods. Depending on the severity of your algae problem and whether you have fish or other plants in your pond, you can choose the right method for your pond to stop algae growth.

Step 1

Control the light to stop algae growth. Minimize the amount of light that penetrates the pond's surface by adding floating and surface-dwelling plants, such as water hyacinths and water lettuce. You can also try adding submersed plants with large foliage that floats on the water's surface, such as water lilies and lotus.

Step 2

Minimize the nutrients that algae needs in order to grow, including nutrients contained in rain water. Make sure all gutters and downspouts are not directed toward your pond to minimize the amount of rainwater that gets into your pond. Build a raised lip around your pond to keep rain runoff out of your pond.

Step 3

Limit the amount of carbon dioxide in your pond to stop algae growth. Add to your pond some oxygenating plants that will use up the carbon dioxide before the algae can get to it. Elodea is a popular oxygenating plant.

Step 4

Keep your filter clean and working properly. Clean your pond filter at least once every month to keep it free of debris. A clogged filter will end up killing the bacteria that grow to breakdown fish waste. Pond water that is not filtered properly will be full of nutrients which enhances algae growth.

Step 5

Install a UV sterilizer. When the pond water is pumped through a UV sterilizer, the device kills any algae in the water.

Step 6

Add an algaecide to the pond water. Liquid types of algaecides are very effective in killing algae but can also kill your pond plants. Be sure to read the label and use a liquid algae inhibitor that won't harm your plants.

Tips and Warnings

  • Don't overfeed if your pond contains koi or other fish. Uneaten fish food is another source of nutrients for algae. Make sure that all the fish food is eaten within five to 10 minutes. Be sure to get the proper size of UV sterilizer for the volume of your pond. If you install a UV sterilizer that is too small for your pond, it won't have any effect on getting rid of the algae.

Things You'll Need

  • Water hyacinths
  • Water lettuce
  • Water lilies
  • Lotus
  • Elodea
  • UV sterilizer
  • Algaecide
  • Barley straw


  • Control Pond Algae with Light, Nutrient Control, Filtration & Algaecides

Who Can Help

  • How Do I Get Rid of the Algae in My Pond?
Keywords: kill pond algae, stop garden pond algae, stop algae growth

About this Author

Sarah Terry brings 10 years of experience writing novels, business-to-business newsletters, and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.