I seem to remember reading a post by someone who controlled floating duckweed by stringing fishing line from one side of their tank to another. I don't remember any particulars of how to set this up. Anyone have an idea or experience with this? :help:
FYI I think this is the thread you are talking about. It has a photo of what I did with my Salvinia minima using fishing line. It's less conspicuous than tubing.