What color dye should be used to act as a light screen for aquatic plants?

Using blue dye is effective for acting as a light screen for aquatic plants due to the way it interacts with light in water. When blue dye is introduced to a water body, it absorbs certain wavelengths of light, particularly in the red and green spectrum, while allowing blue light to penetrate. This selective absorption reduces the overall light available for photosynthesis, which can inhibit the growth of unwanted aquatic plants.

By decreasing the light intensity that reaches the plants below the surface, blue dye helps to control their growth effectively. Control of aquatic vegetation is crucial in maintaining healthy water ecosystems and preventing issues such as eutrophication, which can result from excessive plant growth.

The other colors do not provide the same level of effectiveness in blocking the necessary wavelengths of light that aquatic plants require for photosynthesis.