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Controlling Algae Growth in your Backyard Water Garden

Article Update - June 11, 2008 

What is algae, or more succinctly what "are" algae?

Algae is a group of one-celled plants (subkingdom Thallophyta), having no true root, stem, or leaf. Algae can be a nuisance and can result in more time spent maintaining your pond than enjoying it. Algae is best controlled through a combination of biological filtration and plants. The use of algaecides is not advised since this can result in fish and plants dying due to an increase in ammonia and a depletion in oxygen. 

There are primarily two types of algae that grow in ornamental ponds; string algae and the plankton algae which makes your pond green. Both types of algae grow by varying methods.  String algae is controllable with barley.

Most plankton algaes requires sunlight and nutrients from the water to grow. To prevent excess algae growth, block the sunlight with water lilies or other floating-leafed plants. Use submerged plants, as these plants compete with algae for the nutrients in the water. Dissolved nutrients such as ammonia, nitrite, and nitrate need to be removed biologically. Chloramine Removers & Dechlorinators may help. Biological filters provide a large surface area for beneficial bacteria to grow, dissolving these unwanted nutrients. The surface area of these filters should be as large as possible. Bacteria can take 2-3 months to establish naturally. 

Get rid of any dead and decaying leaves on the bottom or along the sides of the pond.

Remember, it is good to have some algae, such as the small, fuzzy type growing on the walls of your pond. This fuzzy algae acts as a small biofilter, which makes your pond look more natural and gives the fish something to nibble on. "Pea Soup" green algae can be controlled through use of water clarifiers, which will not harm your fish or plants. These clarifiers flocculate the single-celled algae into larger particles which can be removed with a fine net.

Continuously having problems with stringy algae and green water?

• Make sure no runoff from the lawn is entering your pond. 

• There are many commercial Algae Control products that can help.

• Are there enough floating plants to shade your water?   Try a commercial Pond Water Shade

• Are there adequate submerged plants? Raise these closer to the surface if you're facing green water. This will give them more sunlight to grow and "drown-out" the algae. 

• Many snails and tadpoles are good algae control and add to the natural beauty of your pond. 

• Remove all dead leaves from your pond. When leaves are falling try Dewitt's Pond Netting

• It is normal to have an algae bloom in the spring- don't panic though, it takes longer for the floating and submerged plants to start growing again and fighting off that unwanted algae. 

• If the natural approach doesn't work, then try the Pond Water Clarifiers.