I am planning on growing with MH and HPS lamps and I need a ballasts that can be used with both. I have heard of universal ballasts but can't find any info on the web. Can anyone help me out here?
I would just use a HPS light. The easiest and cheap way is to go to a nearest hardware store and buy a HPS security light for the outside. And it's really easy to rewire. Heres a link to help you out with rewireing: http://www.overgrow.com/faq/browse.php?qa=1151 www.overgrow.com is the best site for all ur growing information it will prolly have answers to all of your questions. If you don't wana go throught the trouble of buying the light and rewiring it go here for the ballest: www.1000bulbs.com.
Yep...your looking for a "switchable" ballast...that you merely change the bulb.... here is a link to a site that has such an animal...http://www.thegrowroom.com/lighting.html