New grower grow box setup

[Cannadude]

I'm new to growing but have grown before. I just recently built a box, 5 ft tall, 3 ft wide, and like 4.5 feet long. I made it out of wood and such and i need to post pictures of it but my camera isn't with me. I have it mostly figured out except one thing. I would like to conserve the most space possible, but i am not sure how to do my exhaust... I have a 4 in centrifugal and filter setup so i guess my question is should i put the filter in the box toward the top and run ducting out of the box to my fan and have the fan pull air through the filter and out of the box? or should i have the fan inside the box? PLEASE HELP

 

[Kenngodd1]

I have an ac unit above the grow box with ventilation hoses going into each room. for exhaust i have a bathroom exhaust on top exhausting air into the ac which in turn is getting ventillated to the attic.put the filter insde the box and exhaust fan outside to maxamize space