Im reading it is effective on the weeds i have As far as application goes can it be sprayed on top of the water.with the assumption it is heavier than water it will sink.Or does it have to be sprayed directly into the weeds?With a 2 gallon hand sprayer and a 1/2 acre pond what mixture per gallon should I be looking at.Is it possible to be effective this way or should I be looking at other methods?