Join Date: Oct 2012
Location: Central Florida
Walmart. You need a spiral CFL that has a kelvin rating of 6500k or 6700k. I got a pack of three GE CFL daylight bulbs from Walmart for like $7, so they're not expensive. Wattage doesn't really matter, but I'd stick with the lower end just to be safe.
I think mine is a 13 watt on my ten gallon. Plenty of light, plants grow great.
Good floating plants are dwarf water lettuce, salvinia, and frogbit. You can also use elodea/anacharis and just leave it floating, which is applicable to most stem plants.