The thing is that you dont want it to suck to hard or it will kill them, also you want to attach a cushion or something soft up against the wall of the opposite side where they enter the box! Gives them a soft landing. I also attached a clear piece of hose at the beginning so i can see how fast they go in the hose so i can regulate the pressure at the box! I also put brass corner guards on the outside corners for support, you never know when you will accidently drop the box!...Good Luck!!