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Brandon Boughen: Control the algae in your pond

Algae is very common and will be present in all water that is exposed to the sunlight. However, on occasion, this common inhabitant of water can become overwhelming in farm ponds.

There are three main types of algae in found in fresh water ponds. Chara is a branched algae that resembles flowering plants. It has a musky odor and a “crunchy” feel, and is totally submerged. Single-celled and Colonial algae include microscopic phytoplankton species that occurs in plankton blooms and are usually considered desirable as part of the food chain in fish production. Filamentous algae is most commonly seen in North Texas pond waters. Considered as a nuisance and is seen as a mass of thread-like filaments totally without leaves, often visible in mats that float to the surface. It has been described as a mass of wet wool or bright green hay. These types of algae are the most likely the type that pond owners will be confronted with.

Filamentous algae can be raked or seined from the pond’s surface. This is generally recommended as a first step to control it since it is obviously the “cheapest” method. Another “mechanical” method of control for algae is an “aquashade” product. Aquashade is a non-toxic dye or colorant. It will prevent or reduce algae growth by limiting sunlight penetration. The caution is that these products may suppress the natural food chain of the pond.

Biological controls for algae would include either triploid grass carp or tilapia. The triploid carp is regulated and will require a license from Texas Parks and Wildlife ( The tilapia, which are not in the carp family, will readily consume filamentous algae but are a warm-weather species and will not survive in temperatures below 55 degrees. This may reduce the effectiveness of tilapia in this area since stocking might be delayed due to weather issues. Triploid grass carp will consume filamentous algae, but it is not their preferred food. They will consume other aquatic vegetation first.

Chemical methods of controlling filamentous algae are usually successful and include copper-based compounds, alkylamine salts of endothall and diquat. Copper sulfate, or “blue stone,” is the most common treatment. It will come in several forms, but the smaller crystals will dissolve easier than the larger crystals. This treatment will be less effective in very hard water as it will bind with the calcium present. Cutrine Plus, K-Tea, Captain, Algae Pro, Clearigate and others are all chelated-copper herbicides that are also able to control filamentous algae. All copper compounds can be toxic to fish if used above labeled rates or if they are used in soft or acidic water. Hydrothol 191 is an alkylamine salt of endothall and acts as a contact herbicide. This means that it will work quickly and kill all plant cells it contacts. It can also be toxic to fish.

Pond design and construction can be the most significant method to control unwanted aquatic vegetation. To learn more about these topics, go to the Pond Manager Diagnostics Tool website at

Coming up

The Denton County AG Committee will be conducting a Pond Management Workshop and Fish Fry on April 17 at Rancho De La Roca in Aubrey. The meal will be served at 5 p.m.

This program, which will cost $15 per person, will offer 1IPM CEU for pesticide applicators. Pre-registration and payment is required by April 14.

To register or for more information, contact the Texas AgriLife Extension office at 940-349-2889 or e-mail

BRANDON W. BOUGHEN, MAg, is the Denton County extension agent with Texas A&M AgriLife Extension Service. He can be reached at 940-349-2894 or by e-mail at