Ventilation

I have a grow room that in 10' x 13' I am planning on growing about 5 auto plants for now. My setup includes a 400w Digital Lumatek Ballast running MH for vegging and HPS for flowering and a Cooltube reflector. My question is with a room this big do I really need to run a fan?

You need a fan for the cooltube, no point in using the cooltube without a blower...it'll get to hot. YOu could get away without using a fan if you had an open wing reflector, but enclosed one will get too hot.

you should section room off smaller wit only that one light and so few plants