Well, 15 watt is your limit on the bulbs. And fluorescent lights are brighter then incandescents. Like a 15w fluorescent burns just as bright as a 65w incandescent(well the lights I'm looking at are). But for this bulb it would depend on how the lights go in the lamp, as this would work better going right in and not sideways. http://www.hardwareandtools.com/Eart...b-u784266.html
This would be better for a sideways style. If you had a way, you could put a mirror with the lamp to reflect light so none is wasted, but this would be like a DIY type of thing lol.
Got this from a google search.
It's recommended that when you start out, stick to less than 2.5 fluorescent watts per gallon unless you put a carbon dioxide system in place.
"Cool White" or "Daylight" fluorescent bulbs are cheap, efficient, and effective enough for most purposes.
Also the "color" will depend on the kelvin temperature.