I agree with those that recommend appropriate surfactants. If you want to use glyphosate based herbicides be SURE to use one labelled for aquatic use. Roundup uses a surfactant that is not pond friendly. You are much better off selecting a glyphosate product that is rated for aquatic appications. You then have total control by using the surfactant of your choice.
In my experience surfactants are cheap compared to herbicide costs, and the remedial steps required to recover from damage to my fish, frogs, aquatic invertebrates, and desired plants.
My 2 cents worth...
Frank
