why ask a question with 2 possible answers if you have already decided one answer is not what you want to hear? As for why because I use a 250 watt cfl for 5 plants and get better veg than I did with halide hot expensive to run crap HAHAHA. If you have never done something you dont have a valid opinion on it!!why is this guy tellin me to use cfl's shit what one would be best???? haha
i have used both and the cfl is every bit as effective when used properly in a hydro set up without all the heat issues etc.BUT i would reccommend swapping to HPS for flowering. I am only recomending cfl for veg.well a 250 watt cool white cfl probably would work pretty well, but if you go with mh you will be able to grow your plants bigger....You may want to look into getting an hps instead of mh though cause they are just so much better for flowering. You can get an mh conversion bulb to use with an hps ballast and fixture. U can find really good prices on Ebay....