How To Identify Common Pond Weeds: Tips For Natural Pond Weed Control

By Author: Erica R.
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Duckweed (also referred to as lemna minor) is an invasive and free-floating pond weed that can quickly cover the surface of a small lake or pond. In addition to making the lake or body of water unsightly and not appealing for swimming, these pond weeds can prevent sunlight from reaching deeper parts of the pond. When sunlight cannot reach lake depths, this reduces the natural ability of plants (especially sub-surface plants) to photosynthesize and produce oxygen. Excessive pond weeds and lack of oxygen in a lake over time may reduce levels of oxygen and be detrimental to fish and other aquatic life.


Identifying Duckweed: Duckweed plants are approximately 1/8th to a quarter of an inch in width—they are not very large. Duckweed pond weeds are generally round and have a single root hanging from each individual plant.


Identifying Watermeal: Watermeal is another pond weed and is smaller than duckweed. Watermeal plants look like small garden seeds and are generally less than 1/16th of an inch in diameter. Identifying watermeal is simple—a handful will feel gritty, as if you ...
... are rubbing small seeds or cornmeal between your fingers.


Both watermeal and duckweed pond weeds require a lot of nutrients (both phosphorous and nitrogen) to flourish, they are usually found in lakes and ponds with deciduous trees nearby. These trees drop leaves into the water and cause an overabundance of pond weeds. In other cases, water and drainage from septic systems, feed lots, or other watersheds full of nutrients cause pond weed overgrowth. When you test your lake water or pond water for nutrients, you’ll often be able to identify the source of your pond weed population.


Pond Weed Control: Watermeal and Duckweed


Both of these pond weeds tend to disappear from pond and lake surfaces in the late fall months and reappear in the spring. Spring and summer are when plants photosynthesize and flourish. The process of photosynthesis allows plants to produce “food”, which is stored as starch and oxygen, trapped in the plant’s body for buoyancy. Pond weeds then sink to the bottom sediment where they rely on stored starch for energy. Spring months bring plants back to the surface and start the photosynthesis process again. Pond weed control is essential because with enough nutrients, these pond weeds can bud prolifically and cover an entire pond within a few weeks of surfacing.


Lochness Pond and Lake Dye is available in blue and black colors—these dyes are effective in pond weed control and can safely retard the sun’s ability to penetrate lakes and ponds, reducing photosynthesis. Dye is not recommended for fast flowing (or rapidly moving) bodies of water. Dye can be effective pond weed control in lagoons, sewage runoff, or shallow/muddy lakes and ponds.


To develop a long-term water quality plan to control pond weeds, nutrient levels must be reduced and controlled. Oxygen is a key component in controlling pond weeds and nutrients in a body of water—it’s essential to the health of all aquatic organisms. Without oxygen at the bottom of a lake or pond, harmful anaerobic bacteria produce an acid environment that is detrimental to animals, plants, and other organisms. Learn more about lake aeration and how it can be a solution for pond weed control—visit Clean FLO online.

Erica R. is a freelance writer for CLEAN-FLO International. The CLEAN-FLO Process of Water and pond weed control provides a custom solution for providing aeration in your water-body from bottom to top. Learn more about lake aerators, water & pond weeds control by visiting Clean-flo.com.