Hey guys! Sorry, just a quick question.
So I’m setting up my new grow room. 12 plants. Autos.
Do I really need a 2000 cfm exhaust??
I don’t even know if they come that big.
Room dimensions are 12 x 17 x 9
which is approx 1836 cubic feet.
… I know more info is needed for a perfect assessment. But, am I even on the right track?
AC Infinity either 10" or 12", you’ll need to run 2 fans.
Is this space inside the home and conditioned, as in the house HVAC recycles the air? 
What I was thinking too.
I have seen some of those recommendations for air exchange and wondered who comes up with that stuff. People live in houses with far less air exchange and use far more components from the air than plants do. Turning over all the room air every two minutes is just overkill and I cant see the benefit. A 300 cfm fan would exchange every 6 minutes and that’s still a lot of fresh air. In actual real life it takes longer to exchange ALL the air but still, the plants would be fine as long they are not 100% sealed in and they would get all the CO2 they need if the home HVAC is working. It would circulate your CO2 and you would breath their Oxygen. I have grown for over 5 years without any exhaust fans at all. I see them as more for smell remediation than fresh air in many cases. But I don’t zip my tent either. Light leaks are not an issue in my setup.
I run a 400 CFM 6"Intermittently for and 800 cubic foot room with no problems. The grow room has A/C, but the rest of the house doesn’t so there is no other air exchange for it. I do wish I had gone a little bigger for the noise reduction though. Most of the info I have found recommends an air exchange every 5 minutes or less. I run a bigger fan so it doesn’t run all the time and so I can run it at a lower speed which makes it a little quieter. It doesn’t grow better plants just less noise to bother me. My exhaust does Help to remove humid air and draw in fresh dryer air. That’s mostly why I use one and mostly in flower. I ran an intake for a while, but I felt like it was more noise than benefit. I could see it helping in a larger space though.
Not in this room. It’s a room that is finished, but no heat or AC, above my garage.
Thank you! That’s what I was thinking. Not really necessary. It’s a big room. Plenty of air.
I just need the exhaust for smell (linked to my carbon filter). But kept reading everywhere about removing all air every 1 minute!
Thank you for the reply! 
@1LuckyMF i agree.
Sometimes you might get to a place where you will need the exhaust power for humidity, or heat. I have a 7x14. Initially just used one 6” duct fan. It was fine, until it wasn’t. Had to install a secondary 6” fan. The first one is rigid and behind drywall so I have to rip that off to replace. I have to run 2 dehumidifiers 24/7. If I could go to a 12” right now I would. And I would increase the inlet to eliminate most negative pressure. I’d say get the biggest baddest you are comfortable enough spending the money on. And if you don’t need to use all the power, great. Prolongs its life. Just don’t wanna get stuck in a situation halfway through flower. Plus you are going to need all the carbon filtration you can get your hands on. Surface area is everything. I have 3 carbon scrubbers that aren’t good enough, and using chemicals to cover.
Of course depends on the number of plants and growing methods used.
Thanks a lot. I have a nice one picked out. AC Infinity 8 inch. I was thinking of going with the 6 inch, but after making this thread I better go bigger.
Ty everybody!
I’ll get this to start. Add another later if needed.
AC Infinity CLOUDLINE A8,
https://a.co/d/2P9jtnQ