It has been about three weeks now since I first sprayed my cattails and a few lilies and I am slowly seeing some results. I'm just spraying around my deck but I do have a 15 gal. 12 volt sprayer that can be bought for only $69 on sale and they are a real workhorse for being so cheap. I have used one straped to the back of my lawn more for years and if need be I can put it in my boat for doing larger spraying in the pond. But for the most part I like lots of vegitation in my pond to observe nature.