Air Flow Question..

I'm three days into 12/12 in my grow tent. The 12 hours I have my light on I have the oscillating fan on and my 5" extraction fan with 5" passive air intake. When I turn the lights off I've been turning both fans off so theres no fresh air or air intake. I dont leave the oscillating fan on when the lights are off because I live in a cold climate and it would get way too cold in the tent, Should I be leaving the extraction fan with passive air intake on 24/7??

that is perfectly fine...the girls dont use carbon dioxide when the light are out

Keep an eye on the humidity. It's best to keep it between 40%-60% during flowering to prevent mold. If the humidity frequently surpasses 60% during the night then set the timer to turn the fan on for a few minutes a couple times during the night and you'll be fine.

Thanks a lot GREAT info......... Do u think i might have to leave the fans on when the lights are off next month when there much bigger?