Ventilation 90x60x160

you won't need much for that sized tent. 4" would be fine. can use passive intake (open the mesh vents). With a carbon filter, if needed, might have to run it 75% power and fan noise will come into play more depending on where your tent is. terrabloom is a good fan. Find a duct fan with an "EC motor" that allows 0 or 10% to 100% control. These types of fans last much longer than the slightly cheaper options out there. well worth it. 'can fan' is another good one i believe? ac infinity (puked in my mouth a bit) too. could always jump up to a 6" and run it on low poower with a carbon filter. probably be less noise and if you ever up-size your tent, it will be fine for a 4x4 too. (120x120). 6" carbon filter is quite a bit more expensive than a 4" though. if you don't have to worry about smell, carbon filters are not needed.