A few years ago we planted Lizard's tail in our 1000 gall pond in CT. However, it grows much too well and it has been a battle controlling it. The plant would have taken over the whole pond if I had not pulled out all I could each spring and fall when we take the net is off (for removing lilies). But it impossible to get every root as they are between and under big rocks that form the edge of the pond. So I am thinking about spraying Lizard's Tail with RoundUp (or equivalent). Some RoundUp will doubtless get in the pond, but it's not toxic to fish at the very low concentration that would in the pond. Anyone been successful in controlling Lizard's Tail this way? Or other suggestions?