natural light

Definitely possible! I used to work at a LFS and we had a 180 in the front window. The tank had huge Ozelot and Red Rubin swords some Nymphaea, and Hygrophila polysperma. It was a pretty ugly tank, the plants were just plopped in. No alge problems when I worked there, plus the way the tank is situated in the store, it would be nearly impossble to scrub the glass. Five years later, the tank is still there, Hygro is gone more swords and Crinum, AND NO ALGAE. Come to think of it I don't even think we ever did a water change, just topped it off.