cheers dude. i'll continue with this grow using the hps for flowering as i'm getting a bit low and the time to experiment is when supply isn't an issue. I'll give that a try in my new grow area with some clones that are ready to go in. There just dosen't seem to be any information on these lights on the net. did think about using all four bulbs for flowering, but think the 600whps would probably be cheaper to run and give better results. bought them on a panic after returning from holiday to find one of my plants had grown into the light. all the paranoia about burning my house down resulted in the envirolite purchase. once again thanks.