Thanks, I'll see if I can find some.

I'm currently also experimenting with duckweed growing in my backyard, although I find that it doesn't play well with the other aquatic animals and plants, as it appears to smother them out.

If you have problems with duckweed smothering, azolla will probably be worse. Duckweed has to pull nitrogen from the water, azolla harvests it directly from the air. It makes a good feedstock and fertilizer though.