How important is fresh air from outside in ventilation?

On a scale from 1-10 (with 1 being the lowest and 10 the highest.) How important is fresh air coming from outside into you grow room? ie: flower only room.

I ask this question with the idea of using air from the A/C /heat ducting of the house to run air through the air cooled hoods (hood venting) and exhausted out. (465 cfm) Runs when lights on and 1/2 hour on both sides of on off. Good or bad idea?

Please rate this:
The room air only comes in under and around the door/ cracks or if I open the door and allow more house (basement) air in to the room to exchange the air that gets pushed through a carbon can filter for odor control and exhausted. (465 cfm)

So the question is, is this enough fresh air or:
Should I or do I need to be pulling in air from outside and exhausting that air out to vent the room and lower humidity or cool the room? Temps stay between 78-84 degrees when lights on and humidity is 35-50%. I have an air conditioner that will be installed to keep the temps more stable in summer. At night (dark cycle) the temps will drop to 65 degrees. Room is 7 X 14.

Anyone else doing this or does everyone else pull in fresh air from outside the home?
Please feel free to comment.

It should work though you will want the free flow of air. Why not use/install an intake next to the exhaust for lights. You fan will thank you for it. I was, all winter doing what you discribed and worked fine. There was enough it seemed. Now with window open, bare lamp vertical, fan under on table.
Hope that helps.

bump it up. anyone else?

Well,if you are sucking air out of your grow room,with a fan and through a filter..then new air is coming in. Youve created a strong negative pressure probably..but unless your room is literally airtight..then its sucking in from somewhere else. If you really wanna check if it is sufficient,they sell one time use co2 test kits I think.

It is preferable to have a port somewhere with a mold rated filter over it so you can best avoid sucking in bugs and mold though.

BustinScales510 said:

Well,if you are sucking air out of your grow room,with a fan and through a filter..then new air is coming in. Youve created a strong negative pressure probably..but unless your room is literally airtight..then its sucking in from somewhere else. If you really wanna check if it is sufficient,they sell one time use co2 test kits I think.

It is preferable to have a port somewhere with a mold rated filter over it so you can best avoid sucking in bugs and mold though.

Click to expand...

Not worried about CO2. Have a controller for CO2/ Air exhaust. Is negative pressure a bad thing? Your second statement is what I am very interested in. Tell me about the mold rated filter for bugs and mold. Can this be as simple as some kind of filter sock on the end of 8 inch ducting? Was thinking about using womens nylons over the 8 inch ducting port from the fresh air feed but what does everyone else use? Any suggestions would be great.