the color spectrum is very critical - there's even a special horticultural measurement unit for it - it's called the photosynthesis action curve. essentially, it shows that plants don't use much light in about the center part of the visible light spectrum - that's also why they appear green in color - that wavelength is reflected.
so having a 'balanced spectrum' may not be the best way to grow plants, after all. there's tons of stuff on par on the net, google can help you find it.
here's a chart i came up with to compare brightness.
hey mist: we were growing under mercury vapor lamps long before fluorscents! good old mercury vapor - now those bring back some happy memories...
