Diquat is a weed killer concentrate that needs to be mixed with water before application. Can be used to control pond weed, pond algae, and other aquatic weeds. Diquat is a generic of Reward Herbicide and much more cost effective. Used as a pond weed killer and pond algae treatment and to kill lake weeds such as Water Lettuce, Duckweed, Salvinia, Pennywort, Frog’s bit, Cattails, Bladderwort, Hydrilla, Watermilfoils, Coontail, Elodea, Naiad Algae, Little Barley, Annual Bluegrass, Rescuegrass, Henbit, Buttercup and Carolina Geranium. You will not find a safer aquatic herbicide to kill pond weeds and algae.