A normal, standard HPS bulb is not effective for vegging. It can be used, with success, but the plant will get stretched out budsites during vegging, and by the time flowering is done, you get stretched out, lanky, airy, wispy buds. A standard Hps bulb doesn't give off enough UV rays that the plant needs for that stage. That's why it isn't such a good idea to use JUST an Hps for vegging.

I would use those Floros now that you said you have. Floros/CFL's are amazing bulbs to use for vegging because you can get the plant really close to the bulb without burning. Floro bulbs give off very little heat. So use the floros for vegging, and you HPS for flowering. Your plants will thank you Good luck.