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When to apply aquatic dyes PDF Print E-mail
Thursday, April 18, 2013 1:59 PM

Extension Educator OSU-Extenion Paulding County

Aquatic dyes or pond colorants are a useful technique to control nuisance algae and submerged aquatic plants. Like all plants, submerged aquatic plants and algae require nutrients and sunlight to flourish. These plants can grow only where sufficient light reaches the bottom of the pond or lake. This zone is called the photic zone. Beyond this zone, usually in deeper waters, plants cannot grow. Many factors affect how deep the photic zone extends, including plankton density, water color, and even wind.

Aquatic dyes work similarly by coloring the water a dark blue. The absorption and scattering of sunlight in the blue water significantly reduces the depth of the photic zone. This limits submerged plant and algae growth to only the shallowest areas of the pond or lake. For some pond owners, this reduction in plant biomass may be sufficient to meet their desired pond condition. Other pond owners may need to spot treat with herbicides and algaecides or introduce grass carp to eliminate remaining plants.

Dyes do not inhibit growth of all aquatic plants found in Ohio ponds. Dyes are recommended for use on submerged plants, such as pondweeds, watermilfoil, and coontail. Dyes also inhibit growth of filamentous algae, mat-forming algae, and single-cell planktonic algae. Dyes do not inhibit the growth of emergent plants, such as cattails, and are not effective in controlling floating-leaved plants, such as duckweeds and water lilies, once their leaves are floating on the surface.

The keys to effectively use of pond dyes are to make the initial application in early spring prior to germination. Pond owners are encouraged to apply dyes by April 1 if possible and certainly by April 15. This early application limits sunlight penetration, which in return, delays the growth of aquatic plants that later can become a problem in all but the shallower areas of the pond.

An early aquatic dye application can halt an early growth of aquatic plants before they have a chance to reach nuisance levels. When sunlight is reduced, plant growth is delayed due to lack of photosynthesis. Owners need to be aware that treating a pond having an overabundance of submerged plants with a dye can trigger a fish kill.
More specific information on application rates, weeds controlled, and water-use restrictions can be found on the product label.


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