This is a discussion on Duckweed within the Beginner Planted Aquarium forums, part of the Beginner Freshwater Aquarium category; -->
I used to have a ton of duckweed. I was looking in my tank this morning and noticed most of it is gone or ...
You have a couple of options. You can look under the DIY section on the TFK forum for a plant corral design (really cheap and easy) to keep the duckweed at one end of your tank or you can get a sponge filter (just the sponge) and cover your filter intake or wrap the intake with the blue/white "filter floss sheets" and hold that in place with rubber bands.
It all works, just a matter of what looks good to you.
Filter bags work, but seem to clog quickly for me.