You want a set-up something like this. Basically, you need a hood, socket, bulb, ballast, timer...The digital ballast is 30% more effecient than conventional ballasts and runs lots cooler, but a regular ballast works just as well. I don't like the ballast in the hood idea as it creates even more heat. Also, you can get a combo mh/hps ballast and then just switch the bulbs for veg or flower. That's the simplest and most cost effective. Check ebay and you'll see all the different setups they have. A 400 w setup similar to the one pictured with the digital ballast is around $175 and supports both mh and hps lamps.
Thanks guys I'll start searching for a deal on line now , I think it would be well worth another 175- 200 bucks to increase my yield so much, thanks again for the input.
igot my setup from htg [www.hightechgrowsupply.com] if i remember right its on second grow $169.oo had heat issues though if funds allow get one with air cooled reflector & ducting,inline fan etc. mine was the bargain basement one & if you get one without coolable reflector just remember the heat issue i ran mine 7;oopm-1;oopm [veg]&7;oopm-7;ooam[bud] to avoid hottest part of day used 12'' oscillating fan not perfect but it workrd [still working] myself i'm considdering a large cfl from stealth -hydro there are a lot of options do what you feel best suits your needs oh yeah my gro-room 4'x3'&8.5' tall lol
