Aquatic Herbicide - 1 galAquathol K is a versatile, effective aquatic herbicide containing 40. 3% Dipotassium salt of endothall. Hydrilla, Milfoil, and many varieties of Pondweed are among the pest species it controls. Minimal Water Use Restrictions Not toxic to fish Short half life in the environment Can provide season long contol Excellent product for small lakes and ponds Recommended rate of use varies from 0. 45 3. 2 Gallons Acre ft.., depending on pest species.