No ventilation??

Has anyone had a successful grow without any ventilation? I had my plants in a grow box with no ventilation for about a week and they didn't seem to like it. I recently made holes in both sides of my grow box and set up a fan in front of one of the holes and they seem to be doing much better. Is it possible to grow in a small area (I'm talking a 20 gallon plastic storage container) without any ventilation... provided that there is co2 supplemented (via water/sugar/yeast mix)?

Thanks guys

if you have supplemental co2 you dont need any air exchange. without co2 though the plants wont do much in a closed box as the deplete thco2 fast and stop growing then.

So ventillation serves solely to replenish co2?

no, ventilation is utilized to remove heat, from the lamps.... the co2 replenishment is simply an added bonus, another bonus is that air movement will harden the plants, making them more robust.