I didn't mind my duckweed, but it did need to be thinned out each week with water change. All of my filtration and removal seems to have killed it off, though. Right now I'm using pennywort to float. I love it since it's like a vine. Easy to manage (all in one piece), fast growing, I can attach it to something to keep it in one corner of the tank, and it's a good size/shape for bettas to rest in.
betta splendens (domestic) | betta imbellis | betta falx