Other things to consider prior to treatment to prevent failures 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. Control submerged plants with Aquathol. Rodeo works well on cattails, which is the most common emergent aquatic plant.
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, use of water for livestock and irrigation.