My 32 gallon tank gets food once every 2 days, and my 10 gallon tank gets food about 3-4 times a day. The reason? I'm trying to grow guppies in the 10 gallon tank, and the fastest way to make them grow is to feed them nutrient rich food fairly often. The tank is heavily planted so an excess of nutrients is not a concern; nitrate levels are in the 1-5 ppm range, with no water changes whatsoever. The tank water is 6 months old, and the fish love it. In my opinion, planted aquariums work best if they are nearly closed systems. I run my planted aquarium the same way you would run a reef aquarium, with the nitrogen production of the fish carefully balanced to create a viable ecosystem inside a glass box thousands of miles away from where any of the organisms inside call home.
Cool fact: My province (Nova Scotia) has water chemistry very similar to that of an area in Germany where most of the early work in fishkeeping was done. The area was home to the first sucessful tank-raised Tetras, because it's water chemistry is similar to that of the amazon basin. In short, warm up water from one of the few non-polluted lakes (We're downwind of New York... ugh) around here and any fish from South America or a blackwater stream in Asia would be happy to live there.