Most people talk about 2700k red spectrum and 6500k blue spectrum CFLs.
It's really more like red-ish and blue-ish.
2700K CFLs produce some blue light too and 6500K CFLs produce some red light.
This is what I use :
4000K coolwhite'wide spectrum' fluro tube :
and then 'for the reds' 2700K CFLs:
Its all about efficiency.
The 'wide spectrum' flurotube I use does 1200 lumen/18W
The narrow CFLs i use also does 1200 lumen/18W
BUT, a flurotube with a similar spectrum as my CFL does 1500 lumen/18W.
This is because tubes are more efficient per W then CFLs.
This whole spectrum thingy has everything to do with photosynthesis.
Photosynthesis requires chlorophyl which use these spectra :
Do you get the picture now?