Aquatic Weed Control: How To Get Rid of Aquatic Weeds

This page is a general aquatic weed control guide. Using the suggested aquatic herbicides, you can control any aquatic weed species. The aquatic weed category pages give additional information on the different species and specific treatment instructions and options. Follow these guides and use the recommended products, and we guarantee 100% control over all aquatic weed types.

Aquatic weeds can be found growing on lakes, streams, ponds, estuaries, and other bodies of water where aquatic wildlife is present. They are beneficial to the environment, providing natural filtration, food, and habitat for fish. The problem arises when they start to grow excessively. 

Most aquatic weeds, such as cattails, hydrilla, and algae, are harmless. However, they can interfere with recreational activities like swimming and fishing and are usually just an unattractive inconvenience.

When they begin to grow and create large infestations, though, they can cause significant problems and damage if left untreated by blocking sunlight, stealing nutrients, and reducing the living space for fish.

If aquatic weeds are hampered by your water body, we can help. By following our easy-to-follow step-by-step DIY aquatic weed treatment guide and using professional-grade aquatic herbicides, you can get rid of aquatic weeds quickly and affordably.

Identification

Aquatic weeds can be divided into four groups: algae, floating weeds, submerged weeds, and emergent weeds.

• Floating weeds are those that float on the pond surface. These plants don’t have roots and move freely around the pond with the wind. Most floating weeds multiply rapidly and can be difficult to control. Severe infestations can block sunlight from the pond and cause oxygen depletion. (ex: duckweed or water hyacinth)
• Submerged weeds are pondweeds rooted in the bottom of the pond and where most of the plant remains underwater due to their soft stem. (ex: coontail)
• An emergent weed is primarily above the water surface and can support itself. Sometimes, they are completely out of the water, growing in moist soil. These pondweeds are usually restricted to the shoreline but may extend into the pond if the margins are shallow. Some species of emergent weeds have buoyant stems that can form large mats. (ex: water lilies)
• Algae are commonly referred to as slime, moss, or pond scum. Algae can be found at the bottom of the pond or on the water surface.

There are many different weeds that can appear on your body of water. Check out our aquatic weed library to find the aquatic weed you are encountering and find a specific guide to its control and aquatic herbicide product recommendations.

Inspection

An inspection could be simple or complicated, depending on the aquatic weed growing on your water body. Inspection is important before applying aquatic herbicides so you can analyze your issue, the size of your pond or water body, how much you need to treat, and what treatment options would be best for your situation.

Where to Inspect

Walk around your water body and observe any weeds protruding out beyond the water, floating on the water's surface, or submerged underwater.

What to Look For

It would be best to look for the presence of weeds and the severity of the weed invasion.

Measure the pond's surface area and depth. Knowing the size will help you figure out the mix rates. You will also need to consider whether your pond is used for drinking, swimming, irrigating, or housing fish, as some herbicides have temporary water use restrictions.

Treatment

Our top aquatic herbicide recommendation for treating aquatic weeds is Diquat Herbicide because it is labeled to treat many different submerged, emerged, and floating weed types and is cost-effective. 

Prepare to apply herbicides to your pond by mixing the selected product with water in a pump sprayer according to the label directions. This is also the time to put on the necessary personal protective equipment (PPE).

Step 1: Prepare and Mix the Diquat

Before mixing and applying, you must calculate the size of the water body you wish to treat to determine how much Diquat you will need.

For water bodies, the measurement is usually done by calculating the acreage or acre-foot. To do this, measure the length, width, and average depth of the water body in feet, then divide by 43,560 (Length (ft) x Width (ft) x Average Depth (ft) / 43,560 = Acre-feet).

Diquat should be mixed at a rate of 1 to 2 pints of Diquat per 15 gallons of water per acre.

Step 2: Apply Diquat to target Pond Weeds

Once the Diquat is well-mixed, depending on the targeted weed and the water’s depth, you can spray the herbicide over the water along the shoreline, spot-treat emerged weeds, or broadcast spray over the water’s surface.

Some weeds are best treated with a granular herbicide like Cutrine Plus when weeds are submerged as blankets under the water surface, in deep areas of the pond, or ponds with flowing water. These heavier granules can be applied with a hand spreader and sink directly onto the weed beds.

Step 3: Treat only 1/3 of the pond at a time.

During hot weather, weeds die off, reducing the amount of oxygen available in the pond. Treat your pond in small sections, waiting 10 to 14 days between treatments, to ensure fish have an oxygen-rich environment. We recommend using an indicator dye with your herbicide to mark where you have applied your product so you don’t overtreat.

Step 4: Use Vision Pond Dye

After applying aquatic herbicides, we recommend applying Vision Pond Dye. This non-toxic dye will give the water a natural blue color and filters UV light to inhibit algae and weed growth. Follow the label directions for the proper application rate and pour it at the pond's edge. The water’s natural movement will disperse the dye.

Prevention

It’s important to note that aquatic herbicides kill the weed; they don’t address why the weed is growing in the first place.

• Problems like excessive nutrients and organic materials are the main reasons aquatic weeds thrive. Aquatic herbicides are a great tool but do not address the actual problem of excessive nutrients and organic materials. Following up with proactive pond management practices such as aeration and natural water treatments will reduce the accumulation of dead organic material. It can help keep your water clear from pondweeds for years to come.
• Monitor your body of water regularly for issues and apply control products as needed. Also, make sure your pond gets adequate attention so weeds do not creep back up.

Key Takeaways

What are Aquatic Weeds?

• Aquatic weeds can ruin the look of your water body and hinder recreation. Most aquatic plants can be divided into five categories based on their growth habits. These include filamentous algae, planktonic plants, floating weeds, floating-leaved weeds, submerged weeds, and emergent weeds.

What are The Best Aquatic Herbicides for Getting Rid of Aquatic Weeds?

• Select the best aquatic herbicide for treatment. Our recommended herbicide for aquatic weeds is Diquat Herbicide.

Preventing Aquatic Weed Reinfestation

• After treating the weeds with aquatic herbicide, we recommend using Vision Pond Dye. This Product improves the look of your water body and discourages the growth of algae and weeds by inhibiting UV sunlight on the water surface.