Homebox xxl

I'm just wondering if anybody has one of these, and can tell me why when I turn my fans on that the sides of the homebox suck in like a motherfuc^&r.

I have one. Its called negative pressure, fans create low pressure in the tent and force air to suck in through the intake flaps. It prevents odor leaks if you have carbon filters.

A good tip, something that worked well for me anyways is to leave the bottoms unzipped. Only on the long sides. It helps with intake if you got big fans.