Fans for intake/exhaust

computer fans dont do the job u got to use so many it makes more sense to get a one fan then fool with power adapters get a mini squirel ( and yes i know it didnt spell it right ) cage fan or a bath fan that u can run on household current

How big exhaust for room size (9m x 9m x 4.5m) ?

do the math. you have all the needed numbers right there. then need to change it to cubic foot. unless you have a metric sized fan. thats big so need a few fans to operate it right
9 meter is about 18 foot. so do........18x18x13=4212 cubic foot. then need to add for heat or humidity amount of lights used, bends in hosing. length to vent it out....so on. want to exchange air every 3 to 5 minuites.

ok well when i come around some cash ima go shopping for supplies
thank you for all your help guys. ill post updates and what not

having a proper set up room is the most important item to spend on. never mind genetics or nutes. without a properly function room nothing will work as it was meant to, then we blame the foods or seeds