I like using a incandescent hood with two CFL's. I would start at maybe 10-13 watts. The reason I like this setup is that you have so much adjustability compared to using florescent tubes. You can start at a lower light level and increase as your plant mass increases. Go to far, just put the old bulbs back in. I use daylight bulbs in lamps and other places but it bugs some people. If it doesn't bug you, you are really only out the cost of 2 bulbs because you can use them elsewhere if you go to dim/bright as you experiment with different amounts of light.