Algae is more of an annoyance than serious issue in many ponds. It typically does nothing more than lower the aesthetic worth of the pond and can be somewhat beneficial to get a balanced ecosystem. When the algae begins to grow out of control, it can certainly take over the entire pond and suffocate aquatic wildlife and plants. Many distinct kinds of algae control products are easily available to keep your pond free from this aquatic nuisance.

Pond Dye

Pond dyes function by darkening the water, which reduces the amount of sunlight that penetrates the water. Without proper sunlight, algae cannot grow. Pond dyes will not harm aquatic wildlife and can be utilized in ponds where fish are present. For effective algae control employ the pond dye in March or April, suggests the Ohio State University. Most aquatic dyes have been pumped right into the water and will spread through the pond. For best results, follow the directions on the pond dye label.

Aquatic Herbicides

Copper sulfate is a contact herbicide used to effectively control different aquatic weeds. According to the South Dakota State University, copper sulfate provides excellent control of algae. Unfortunately, if used badly copper sulfate can damage and kill the fish living in the pond. Prior to using copper sulfate in ponds containing fish, then test the alkalinity of the water. Applying copper sulfate to ponds with an alkalinity level below 50 parts per million might kill the fish population. If the loss of fish isn’t a concern or no fish are found in the pond, then testing the alkalinity level isn’t important.

Barley Straw

When barley straw decomposes in the water, it releases compounds that interfere with the algae plant cells. This disturbance prevents new algae cells from growing. Barley straw does not control algae already present in the pond but may also prevent future development from appearing. The Ohio State University recommends using it at a rate of 0.025 pounds of straw for every square yard of foot. Normally, barley straw decomposes fully within four to six months. Barley straw does not damage aquatic life and is safe for use in ponds with fish.

Algae Rake

Filamentous algae is sometimes called pond scum or moss and it forms strands intertwine together, developing a mat or clump of this plant. Having an algae rake you can manually get rid of the aquatic plant from the pond without adding dyes or chemicals to the water. Algae rakes function in the same manner as a leaf or garden rake does. Drag the rake across the surface so the “tooth” of the rake can snag the algae and then pull it out of the water.


Grass carp are a natural control option for filamentous algae in ponds at least 8 feet deep or in case an aerator is existing. Bear in mind that a number of forms of grass carp are considered invasive and should not be utilized. As an example, the Chinese grass carp should not be utilized in the state of California and instead choose the triploid grass carp to control algae. Some areas may need a license to possess grass carp in ponds. To learn more contact your regional Department of Fish and Game.

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