For starters CFLs Advantages:Low electricity cost, their inexpensive, don't build up heat and can be kept inches away from plants, and they come in a variety of spectrums, Disadvantages:You need a lot of them and they just aren't as bright as HID lamps. Their still good for growing great dope. You should use atleast 10,000 lumens per sq/f with these if you plan on growing more than a couple plants the average 25w CFL is about 2,000 lumens so add it up. As for spectrums the 6500k and 5000k are the most common kelvin temperature use for vegative growth and 2700k for flowering a 2700k can still be used for vegative growth but a 6500k or 5000k should never be used for flowering as this can create popcorn fluffy buds. These should be kept at around 6 inches from the canopy of the plants too get the most out of the lumens given out. What are you going to be growing in? So I can give you a rundown about air circulation.