Turn off any pond filters and skimmers. Keep on any aeration such as water and air pumps.
Fill a bucket with water from the pond.
Pour the required amount of chemical into the bucket. Follow the label on the packaging. For example, for every 1,000 gallons of water, you need 1 g of Dimilin-, an example of a chemical used to kill anchor worms.
Mix the chemical thoroughly in the bucket, then pour the solution over the surface of the pond. If the pond is large, pour the solution around the shallow edges and around the water pump or aeration pumps.
Check daily for dead snails. Remove dead snails from the water with a pond net to avoid decomposition and a decrease in water conditions.
Place large lettuce leaves or pond lilies in the pond and let them float.
Scoop up the lettuce leaves that accumulate snails daily and remove the snails from the leaves.
Place the lettuce leaves back into the pond to accumulate more snails. Once the leaves start to wilt or float under the water's surface, replace them with fresh leaves.