I have, for lack of a better term, a duckweed infestation. I've been scooping out some of it every day, but it's tedious and seemingly ineffective, as it multiplies every night.

I am running a 40 breeder with medium light and CO2. I'd love to get rid of most of the duckweed (all of it?) so that more light can reach the bottom of the tank, if possible.