There are many species of aquatic weeds, any specific species can be considered either a aquatic weed or a beneficial aquatic plant depending how the species is impacting upon the use of the pond or lake. Excessive growths can interfere with swimming, boating, fishing, irrigation, fish harvesting, and flood control. As we mentioned before, aquatic weeds fall into three categories.

Submersed Weeds

Submersed weeds grow beneath the surface of the water and are rooted on the bottom of the pond or lake. Submersed weeds when not present in excess provide spawning grounds for the fish, cover for the smaller fish, provide oxygen and tie up nutrients that might otherwise be made available to more objectionable plant growth such as algae. Submersed weeds can be eliminated in selected areas, it is not necessary or generally desirable to kill all the weeds in a pond or a lake. Most of the chemicals for weed control can be used on a selective basis, making it possible to treat just the area where the weeds are a problem and leaving large portions of the pond or lake with weed beds that can help maintain a natural balance in your body of water. Some of the aquatic herbicides that we handle for submersed weed control are, Reward, Sonar, Navagate (2,4D Granular) Aquathol K (liquid & granular) and Hydrothol Granular. Which product is best for your problem depends on what species of weed that you have and what you are using the water for. If you are looking for specific recommendations for your pond or lake, it is best to send us a weed sample so we can determine which product is best for your situation and the species of weed that you have.

Floating Weeds

Floating weeds are those that float on the surface of the water, the most common are duckweed and watermeal. Floating weeds are generally not a problem in larger lakes or flowing water situations. In smaller ponds this type of weed can completely cover the surface of the water to the point where it looks like your pond is an extension of your lawn, only a slightly different color of green. Unlike submersed weeds, if floating weeds get to problem portions the entire surface area of the pond must be treated. Once a pond is covered with duckweed or watermeal, all the sunlight is blocked out to the bottom of the pond, this being the case it is highly unlikely that you will have any beneficial submersed plants to be concerned with. What we normally recommend for floating weeds is a product call Sonar, which will give a total kill. Once you have eliminated the floating weeds we recommend you consider using an aeration system to get the water in the pond moving, creating a hostile environment for the floating weeds. We also recommend planting some submersed weeds to tie up the nutrients to further prevent the duckweed or watermeal from coming back.

We can also recommend the use of a product to inactivate excessive phosphate from the water, which helps reduce algae and floating weed re-infestation.

Emersed Weeds

Emersed weeds are those that grow out of the water and most of their foliage is above the water line, the most common are Cattails and Bulrushes. The main thing to keep in mind when treating a emersed weed, is that there needs to be enough foliage out of the water, so that the foliage can absorb enough chemical to get down to the root of the plant. When treating Cattails the best time to treat is when the Cattail is first developing it tail, once you have treated the plant you should wait 2 - 3 weeks before cutting down the plant so the chemical has time to get down into the root system. Most emersed plants can be treated with either Reward or Aqua Pro and a good sticking agent (Cidekick or Silenergy).


General recommendations for successful weed treatments

1. Treat on the morning of a sunny day.

2. Make sure to evenly spread the aquatic herbicide over the area to be treated at the recommended application rate.

3. Water temperature should be above 55 degrees, except in special cases.

4. Treat only when the weeds are visible, unless using Sonar herbicide.


Aquatic Systems has available a complete line of both aquatic algaecides and herbicides. For recommendations and pricing, give us a call at 866-442-0420 or drop us a line or email..

......