Control Duckweed in your Pond with Aquatic Herbicides

Duckweed is one of the fastest growing organisms in the world. It can multiply extremely quickly and take over a small pond in just a few days. Larger ponds and lakes can become infested and covered with duckweed in as little as two weeks under the right conditions. It is also easily spread from different bodies of water by birds and other animals. This is why most pond owners are eventually faced with a duckweed problem that requires chemical treatment to get under control.

Not only does a thick mat of duckweed ruin the appearance of a pond, but it can also harm other plants and animals in the pond, and if left untreated can cause damage to the ponds ecosystem that can take years or even longer to recover from. Another problem with leaving duckweed untreated is that it will continue to multiply and grow even after it has completely covered a pond. This excess duckweed forms thick clumps and begins to rot, releasing a foul smell and turning your beautiful, pristine pond into an ugly stinky swamp.

duckweed pond

Duckweed Eventually forms thick clumps and begins to rot, releasing a foul odor.

Luckily there are several duckweed control treatments on the market that are extremely effective at treating duckweed, without harming other desirable plants and animals in the pond. The most cost effective and widely used aquatic herbicide is Sonar Aquatic Herbicide. Sonar is favored by many pond owners because it is safe to use with other plants and animals present in the pond. It controls target weeds selectively, allowing desirable vegetation to remain unharmed. Sonar also does not deplete the oxygen in the water, making it completely safe for fish.  Ponds treated with Sonar are also completely safe for swimming. Pond owners can rest easy knowing that Sonar has been used to safely treat duckweed and other aquatic weeds in thousands of ponds across the country for almost 20 years!.

Aquatic Herbicide Duckweed Treatments

A full treatment of Sonar takes about 90 days, but you should start to see significant results after 30 to 60 days. Duckweed in a medium to small pond may be under control in as little as a month, but it is still strongly suggested that you continue treatments for the full 90 days to thoroughly control duckweed. Applying aquatic herbicides is generally more effective early in the growing season, before duckweed and other aquatic weeds have a chance gain a firm foothold in your pond, but applying later in the season is certainly still effective.  After a full Sonar treatment, duckweed and other aquatic weeds will remain under control for a full season or longer.

Sonar Aquatic Herbicide duckweed treatment comes in two forms: Sonar AS (liquid) and Sonar Q (granulate).  Application rates depend on the volume of the pond and the types of weeds being targeted, generally between 1 and 1.5 quarts per acre for a normal pond (4’-6’ avg depth). If you know your ponds volume you can measure per acre foot. Complete directions and application rates are on the label. For those looking for a complete pond treatment system, there is the PondPak, which includes several other formulas to eliminate harmful weeds and restore nutrient levels to a proper balance. The PondPak is a great deal for those looking for a more permanent solution for duckweed and other aquatic weeds.


The Sonar Brand Aquatic Herbicides can be a little on the expensive side, but they are the best on the market for safely treating ponds and eliminating duckweed and other aquatic herbicides. If you are looking for a cheaper alternative and have a smaller pond, then you may be in luck. There is a generic version of Sonar called White Cap Aquatic Herbicide that is cheaper than Sonar, and also comes in a smaller quantity.


For the best prices we suggest Not only are their prices always at or below other sites, but they also offer free shipping on these products, which can save over $100 in shipping costs alone vs other places. Of course before applying any chemical to your pond make sure you check with your local authorities to make sure that it is allowed in your area.

Duckweed Prevention – How to keep duckweed out of your pond

After spending considerable time and money controlling duckweed in their pond, the first question most people have is “how can I keep duckweed from coming back?”  There are several ways to prevent duckweed from growing in your pond, but another question you need to ask yourself is do you really want the pond to be completely duckweed free?  Even though duckweed can be a nuisance plant in our ponds, it is also a naturally occurring and beneficial plant in most areas.


Duckweed’s role in a ponds ecosystem

Before you go and try to totally eliminate duckweed from your pond and make it duck weed proof, you need to understand the part duckweed naturally plays in a pond.

Duckweed is a valuable part of many aquatic environments around the world.  The lemna minor plant and its relatives do many beneficial things for ponds and lakes that help other species survive and thrive.  Duckweed is a major source of food for [...]

Controlling Duckweed – Long Term

Unfortunately it is nearly impossible to keep duckweed out of a pond.  It is spread by ducks, birds, and other animals when it sticks to them and they move around to different ponds and lakes.  So unless you have found a way to keep all wildlife out of your pond, you will also have to deal with duckweed at some point.

Duckweed is a natural part of many aquatic ecosystems…

but its ability to spread rapidly and choke out other species means it is prone to causing serious damage, especially in smaller ponds.  Remember, duckweed is much easier to treat in its early stages, before it has had time to multiply.  Duck weed colonies can double in size in less than a day, so it is important to stay ahead of the infestation.

How to Control Duckweed Long Term

While there are many different methods of treating duckweed and controlling it short term.  The only viable long term duckweed control [...]

Duckweed Facts and Information

The duckweed plant and its relatives grow around the world on every continent except Antarctica.  It can be seen as a nuisance and unwanted intruder in ponds and lakes, as well as a vital food source and important part of the ecosystem, depending on where it is found.  Here are a few quick facts that you may not know about the common duckweed plant (lemna minor).


Duckweed Is Important to Many Animals

Most people know that many animals including ducks, fish, and birds eat duckweed, but did you know that many animals also use duckweed as cover and a hiding place from other animals?

Frogs commonly use duckweed to escape and hide from predators, both on land and in the water.  When a frog feels threatened on land, it will attempt to jump into a mass of duckweed near the shore where it can instantly disappear underneath a layer of green weeds.  Frogs and many fish also use duckweed [...]

What animals eat Duckweed

Many different species of animals are known to eat common duckweed (lemna minor).  Birds, fish, mammals, reptiles, insects, amphibians, and crustaceans eat it.  Even humans eat duckweed in some parts of the world!  This is because of its high levels of protein and other nutrients, as well as its fast growth rate and easy harvest methods.  Duckweed is a major food source for many fish farms for these same reasons.  Alternatively, certain fish can also be introduced to ponds and smaller lakes to control the growth rate of duckweed.


Birds and Ducks

As its name suggests, ducks do indeed eat duckweed, and it is a major part of their diet when it is found in their habitat.  Ducks do not generally eat enough duck weed to have a noticeable impact on its overall growth rate or surface coverage.  In addition to ducks, many other birds will occasionally snack on lemna minor.



Many kinds of fish eat duckweed, [...]

Types of Duckweed And Related Species

Duckweeds are small aquatic plants that float on or near the surface of slow moving or still waters.  They are common around the world in lakes, ponds, swamps, and river backwaters.  All duckweed species reproduce very quickly and can cover entire bodies of water in thick mats of vegetation during warm summer months.


Common Duckweed (Lemna Minor)

Common Duckweed (lemna minor)

Common Duckweed is by far the most widespread species of duckweed throughout the world.  Also known as lesser duckweed in some places.  Common duckweed is native to every continent except Antarctica and is able to survive in waters ranging from 40 – 90 degrees Fahrenheit (5-33 C). This allows this species of duckweed to thrive in a wide range of environments around the world.   It is generally light green colored, though different climates and water types have slight color variations.

Common duckweed floats on the surface of water and has between one [...]

Duckweed Control – Chemical Free Methods

Non-Chemical Duckweed Control Methods

Duckweed has an extremely fast growth rate under the right conditions and can quickly cover a small lake or pond if left unchecked.  In waters with high nutrient levels duckweed can double in population every 36 hours.  When duckweed covers a body of water it prevents sunlight from reaching the bottom and impairs the growth of algae and other underwater plants.  This can in turn lead to reduced oxygen levels and fish kills.  To prevent this, something must be done to control the growth of duckweed on a pond.

Although there are several chemical treatments to control or kill duckweed, many people prefer to try chemical free methods before resorting to expensive chemicals with strict environmental controls and rules.

There are several non-chemical treatments for controlling duckweed growth, but they all have their limitations, and only one will completely eliminate duckweed from a body of water.


Duckweed Skimmers

For very small ponds skimmers can be [...]