Necessary to vent when the lights are out?

Is it? Or can I kill the fans and give it a rest when there is no heat other than what the plant is kicking off? I was thinking about humidity too. Maybe running a small de humidifier or some desiccant in the tent. Just thinking ahead.

i think the idea is to keep an exhaust fan going 24/7. that will exchange the CO2 with fresh air. and, like you said, it will vent off humidity and hopefully prohibit mold. as far as the oscillating fans go i think you can kill those in the dark. personally i run them all 24/7 but i don't know if that's recommended or not.

I agree with stvitusdance I keep mine running 24/7

I also agree. My oscillating fan and exaust fan run 24/7.

if you dont have negetive pressure on your grow area smell will begin to seep out

I keep my intake (which is powered) bringing in air from outside 24/7. My exhaust + filter is on a timer, an hour after lights out it comes on only 15 min per hour, my oscillating fan does the same. Personally I've experienced no issues, but everyone's grow is different. My area is not sealed. Plants from what I've seen tend to kick off a lot of smell just after lights out so you'd definitely want your fans running then.

i agree, keep 'em running. i do it mainly to prevent mold. GL