I need advice on a grow design.

I know I'm posting the same thing in two separate boards, but I couldn't decide which one was best to put it in.

Just a couple questions on a hypothetical design, done just for fun.



Considering that the box is lightproof, and everything shored up with light catches, I'm wondering if a computer fan will create enough negative pressure inside to bring in enough CO2 to feed the plants.

My walls wouldn't be coated with any kind of mylar, and would be the natural wood grain, I realize that this is normally frowned upon, but seeing as I'm using a huge light, I don't see how this would be a problem other than to slow down growth. Could I get away without coating them?

Seeing as I have a florescent light specified in the plan, I'm worried that the box might get too cold, is there any way to fix this other than putting in another light? Maybe insulating the box a bit?

Last question, hypothetically, I'm against using chemical ferts.
Could I get away with using nothing but a natural manure mix?

Thanks guys, I appreciate the review.