First Theoretical Grow. VeggiePro by Aerogarden. Ventilation?!

I have set up a box in my attic. I have the seedling (white widow feminised by Greenhouse Seeds) in the veggiepro and it looks like its doing great. I want to know how much ventilation this single plant will need. I have access to the tube that vents the bathroom steam but I don't know if that will cover it, or could I get by with opening the box once or twice a day?

-thanks

I should say that it is a cardboard box and would be able to put some computer fans in the sides if necessary.