Many different plants grow in and around the pond. They convert sunlight energy into organic materials; the basis for dissolved oxygen in your pond. When there is an overabundance of plants, they become aquatic weeds. Control of aquatic weeds can be tough, especially algae. There are two types of algae, filamentous and planktonic. Filamentous is often seen as a yellowish green mat on the surface. This algae starts life on the bottom of the pond and feeds on oxygen as it nears the top. This occurs after very low levels of water allow the algae to be exposed on the bottom or disturbance causes it to break free from the bottom and circulate through the water. Planktonic algae is a microscopic plant floating in the upper few feet of water. It appears as soup green, brown, or bright green colored paint split on the surface. Copper Sulfate is one method of algae control. Follow the label recommendations for best results and do not over apply.