Sonar is an aquatic herbicide effective in treating a variety of submerged, emergent, and floating aquatic plants. It is especially useful in the treatment of duckweed and watermeal. It is recommended that Sonar is applied when there is no flow of water out of the pond. Sonar can take up to 45 to 90 days to become fully effective. It is recommended that you contact an ATAC pond management expert before utilizing Sonar to discuss the optimal treatment rate/procedure.