Thanks a lot guys for the advice. I definitely do not and will not have a problem with low tempatures. If bottles can last long enough and be somewhat cost effective, I will just deal with that since there isnt a natural gas or propane hookup in the room. I am an avid welder so they know me at the welding shop, buying a lot of co2 is chill. I am also using air cooled hoods.

My next question is...how long to let it soak without the fans? An hour? How many times a day?

I dont think I will play with a ring above the plants unless there are serious advantages, although that would be rather easy to make with a torch. I like the idea of a light-action fan moving it up into the air from the floor, but it wouldn't be hard to run a line to the ceiling.

And I was slightly confused by your remark about the night. At night plants produce their own CO2, so I dont need to worry about it? Is that what your saying?