Round-Up is not approved for use in water because it is the surfactant (adjuvant) that tends to be problematic. One good glysophate plus surfactant mixture in one jug is Shore Klear Plus (usu sold in gallon size & then diluted & sprayed) made by Applied Biochemists - the "Aquashade people".


aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management