Hi, I was planning on building a stand to grow orchids under lights with my Dad, and I was wondering how far I should have the lights above the plants if I use T-12 lights? I am planning on having two, two bulb ballasts on each of the two levels. I need to know the distances because I am going to be using leftover hardwood from our new house we built! Any input would be GREAT! I will post pics once it is built.(If I can figure out how to !)