Reduction of plants in the spring or early summer before large growth occurs usually prevents oxygen depletion. If treatment is not done until heavy growth occurs, treat the pond in sections with at least two weeks between treatments. Other things to consider prior to treatment are adverse weather conditions or high water exchange in the pond. Chemicals are registered for specific uses and few are cleared for aquatic use. Cutrine is effective on algae.
Rodeo works well on cattails, which is the most common emergent aquatic plant in Colorado.
Many chemicals have restrictions on the use of water for a period of time after application. Follow the directions on the label and read restrictions on fishing, swimming, and use of water for livestock, and irrigation. To obtain names and addresses of most major herbicide manufacturers and distributors in Colorado, contact your Colorado State University Cooperative Extension county office. References How to Identify and Control Water Weeds and Algae . Applied Biochemists, Inc. 5300 West County Line Road, Mequon, WI 53092.