Carol, I don't have any 2' fixtures, but here is what I have in my "Orchids Only" greenhouse. I have two, 4' x 6 T5H tube fixtures on one side. They are end-to-end, and thus gives me 8' of light. I hang those fixtures about 18" above my top shelf of orchids (no closer than 8" from the leaves though). They get hot and I think the total lumens for each fixture is rated around 25,000 lumens. They are really, really bright.
On the other side I have four, 4' x 2 T8 fixtures, placed side-by-side and end-to-end. Again, I have 8' of light but two deep. Each of those fixtures is rated around 5,000 lumens. Compared to the T5H fixtures, though both the T8 and T5H are 6500K tubes, these T8 lights are "dull"! They are also cool and I can place plants within 3" of those with no problem. I am leaving these T8 fixtures as-is for now, but will replace them next fall with the same T5H fixtures I use on the other side.
I have a light-meter ordered and when I get it in I will know how much light there (really) is under the various light arrangements I have in my two greenhouses. I will post that info then.
