Hornwort, Moneywort, all the -worts! Those floating plants do a lot of heavy lifting in my tank, as well as red foxtail, and duckweed. Actually, I found duckweed to be a bit of a curse - it grows crazy fast, and I finally phased it out (with the help of a gravy ladle!). Mixed in with the duckweed that I bought was a few of some kind of quite similar plant, just much larger and easier to deal with, and that has reproduced to take the place of the tiny PITA duckweed. I am not sure what this "greater duckweed" is called, sorry.
Keep an eye on your fishs behavior, it can indicate unhealthy water, and do water changes as necessary. I don't even use a powerhead, and all is going well so far. No algae, clear water, and content fish and snails.