Nutrients are the main cause for excessive aquatic plant growth.

Only a small amount of nutrients added to a pond can cause a lot of problems with aquatic plant growth. Nutrients can be added to your pond in a number of ways, such as, leaves, grass clippings, wildlife waste, and runoff from lawns, cattle pastures, and farm fields all add a large amount of nutrients to your water. Once they reach the pond, they are available for plant growth.