Aquatic plants, just like plants on land, need light to grow. In ponds we address light penetration into the water by adding pond dye. Pond dye essentially creates a higher reflective surface on your pond so that less light reaches the bottom, where plants start to grow every spring. It works best at depths greater than six feet and will not be as effective in the shallow areas around the edges of your pond. Pond dyes work on the premise that plants grow poorly without light so blocking it will reduce your growth in the main body of the pond. Pond dyes are available in blue, which you commonly see at golf courses, and black, which give a more natural Muskoka water look. Pond dyes are most effective if added early in the spring as soon as the ice is off the pond and before growth starts. They are non-toxic and are safe for humans, pets and wildlife alike.
To decrease plant growth in ponds you could also explore nutrient management strategies by using probiotics and manual removal.