Greenguy,
I have a thread on just that question linked in my signature. All I use is commercial HID lights converted to remote ballast set ups and there are many options for hoods/reflectors. There are also related threads on different DIY light setups and reflector/hoods in the DIY section that can be adapted to almost any kind of light.
ZEM, is pretty much correct that so long as you can turn it off or on, any commercial light of a given type can be used in a grow application; PROVIDED THAT IT IS A LIGHT OF A SUITABLE TYPE --i.e. CFL, MH or HPS and not Mercury Vapor, Halogen and so on.
You will find as many different recommendations on reflectors/hoods as you find growers ready to give the advice.
I suggest you check my thread on the conversion and the one on making your own 6" air cooled hood (they are linked in my signature) and then ask specific questions. Also, when you get into the specifics, detailed photos are a great help to everyone in getting appropriate advice to you.
If you are willing to live with slightly more heat and sometimes slightly more noise and always having to have type specific equipment rather than switchable ballasts, then converting commercial HID and CFLs is a very economic way to go. And of course recycling the commercial stuff rather than having it thrown away and new "grow" lighting built is much better for the environment.
I think I'll be seeing more from you and if you decide to go this route I'm sure you will be glad you did. I am paying $30 to $35 per commercial 400 watt HID and by the time I get them converted I have approximately $50 to $55 total invested plus on the average 3 hours of conversion labor, and that is a relaxed 3 hours -- it can be done in way less time than that if you want to really hustle.
Great smoking.
