Ventilation Help

I am going to be constructing a 3x3x5h box with a 400watt HPS light. I have the lighting, space, and all that down but i have no clue how to set up the ventilation. I know the temps need to stay around the 80 degree mark give or take a little. I would greatly appreciate if someone could tell me the correct way to go about making the ventilation for this box along with odor control. I know i will need 2 fans but I'm not sure what fans to use, where to put them, and what else goes along with the fans.

THANKS!!

Intake fan goes anywhere from half way up the box to 1/4. Exhaust fan goes anywhere up near the top, as high as possible. This will allow cool air to come in and warm air to exit. Careful not to go too powerful when deciding on fans (a "mistake" I'm having to deal with) else the movement of air might dry out the box. Make sure both fans move air at the same rate to keep the pressure equalized as well. As long as a steady stream of air is traveling into the box as well as out of the box you're good.

Duct fans will work if you're on a budget, but I've found that PC fans (high powered ones) work best. They are also pretty quiet. You might have to use a duct fan to move air through a carbon filter if you decide to go that route.