A HPS light has a wider color spectrum then most other grow lights, and I believe it's the closest thing to the spectrum the sun puts out. CFL's are basicly just white light if I remember right, I like using CFL's in cloning, MH in veg, and HPS in flowering, but HPS in veg works great too. Don't waist time trying to flower under CFL's, You'll end up with airy buds, and it will take longer to fully mature!

Grow big or go home!:thumbsup: