bathtub set-up help

Hi everyone, I am setting up a nice little room for my babies in my bathtub, I hung some black 4 mil plastic from the top down to make it light proof. It is an area about 2 feet wide, 4 feet long, and 7 feet high. Using a 400W HPS to light the area. I put a fan in there and it keeps pushing around the "curtains"! not good. how hard does the fan have to blow? this one is a small 9" fan that really kicks some ass. any suggestions? just wish i had sliding glass.... I am planning to cover the black plastic with reflective mylar or white plastic. thanks for any help. heres some pics of my current ladies, enjoy.

Mike

why cant they stay outside, are they to young and its gettin to cold or wut? and for the fan, it can be on low.

those are staying outside, i was just bribing people to help me by showing pretty pictures :D I am going to clone the big ones and grow them indoors starting this weekend.