Killing Duckweed In The Uk

EASY way to Remove DUCKWEED from Aquarium! YouTube
EASY way to Remove DUCKWEED from Aquarium! YouTube from

What is Duckweed?

Duckweed, also known as Lemna minor, is a small aquatic plant that is native to Europe, Africa, and Asia. Duckweed usually grows in shallow, still or slow-moving bodies of water such as ponds, lakes, and marshes. Duckweed is a free-floating plant, meaning it does not have any roots, and instead, its leaves are connected to the stem and float on top of the water. Duckweed is a small plant, usually no more than an inch in size and is often mistaken for algae. Duckweed is an important food source for ducks, fish, and other waterfowl and is also an important part of the local ecosystem.

Why Should Duckweed Be Controlled?

While duckweed can be beneficial to the local ecosystem, it can also be problematic. If left unchecked, duckweed can quickly take over a body of water, covering the entire surface of a pond or lake. This can have a number of negative effects, including reducing the amount of sunlight that reaches deeper water and reducing the oxygen levels in the water. This can lead to the death of other aquatic plants and animals. Duckweed can also be a nuisance, clogging up water systems, blocking out sunlight, and making swimming and fishing difficult.

How To Kill Duckweed in the UK

If you have duckweed in your pond or lake, there are a few methods you can use to control it. The most common and effective way to kill duckweed is to use a chemical herbicide. There are several herbicides available that are effective against duckweed, including Aquacide Pellets, Cutrine Plus Granular, and Copper Sulfate. These herbicides must be applied according to the manufacturer’s instructions and should be done on a regular basis. Once the duckweed has been killed, it should be removed from the water. This can be done with a net or by hand. If you are using a chemical herbicide, it is important to wear protective clothing and to follow safety instructions when using the product.

Other Methods For Killing Duckweed

In addition to chemical herbicides, there are other ways to control duckweed. One way is to introduce predators such as grass carp, Koi carp, and tilapia into the water. These fish feed on duckweed, so if there is enough of them in the water, they can control the duckweed population. Another way to control duckweed is to reduce the nutrient levels in the water. Duckweed thrives on high levels of nitrogen and phosphorus, so reducing these levels can help to limit the growth of duckweed. This can be done by limiting the amount of fertilizer you use in your garden and by not overwatering your lawn.

Preventing The Growth of Duckweed

The best way to control duckweed is to prevent it from growing in the first place. This can be done by keeping the water clean and clear. Make sure to remove any debris such as leaves and sticks from the water and to keep the water aerated. This will help to reduce the nutrients that duckweed needs to grow and will help to keep the water clear.


Duckweed can be a nuisance, but it can be controlled with the right methods. Chemical herbicides can be used to kill duckweed, but it is important to use them correctly and to follow safety instructions. Predators such as grass carp, Koi carp, and tilapia can also be used to control duckweed. The best way to control duckweed is to prevent it from growing in the first place by keeping the water clean and clear.

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