Whitecap is the most effective for the price. Sonar and Avast are overpriced same deal. Where Diquat based stuff will normally wipe duckweed out, that damn watermeal just sits there and absorbs it. Ot maybe does not absorb it, that could be why contact herbicides have less than desirable results on watermeal. Of course, I hope whatever you try works out for you. Just in my experience watermeal is one tough hombre to knockdown. And duckweed is is close, but just not the same. I'd Judgement Day the watermeal.
