venting air cooled light and carbon filter through one fan

hi i have been agonizing over venting systems i have a 7x7x8 room 400 cf i want to run 2 1000 hps with air cool tubes and co2 i think running a one inline 400 cfm fan to pull one line through the lights and one line through the carbon filter with one exhaust into the basement. i was wondering if one fan will be ok for all, the intake for the lights will be out of the room and the intake for room will be from another room in the house. no intake fans

thank you for your time

ps if you vent a c02 filled room into another part of the house is there a danger of filling the house with co2

"if you vent a c02 filled room into another part of the house is there a danger of filling the house with co2"


I am also looking at setting up CO2. One of the most important things when doing so is making sure the grow area is properly sealed. If it is not you will be letting the CO2 leak into the rest of the house where it does nothing good. As long as you are investing in this idea make sure you do it right. Since you have air cooled hoods it seems like a good start. If you are not sure if the hoods are airtight you can apply some of that silver coated duct tape where the hood meets the glass. Hope this helps!

This looked like helpful info, courtesy of

Grow Marijuana FAQ, Cannabis cultivation - marijuana growing tips & photos

How big should the fan be?
Fans are rated in either cubic feet (CFM) or cubic meters per minute in North America. In Eurpose, metric fans are rated in m3/hr - cubic metres per hour (m3/hr).

That means a 70CFM fan will move 70 cubic feet of air in one minute.
Your fan should be big enough to move the volume of your area 2 to 3 times every minute. A 70 CFM fan would be adequate for a 35 cubic foot area, and would be optimal for roughly a 23 cubic foot area.

· To figure your area’s cubic volume, multiply (in feet) the length by the width by the height.

Since it suggests cycling 2-3 times a minute, you should be looking for something at least 1500 cfm since the carbon filter will add back pressure to your system

Your CO2 should not be able to fill the house, you can't just turn the c02 on and let it run continuously, the plants will die if they drown in it. Due to this fact you must have some sort of timed/logic release system that has been adjusted to work on your space requirements. Unless your grow room is larger than your house i wouldn't worry about asphyxiation. the small amount being metered out into a large room would not be enough to cause alarm.

a more ideal set up would be to use your current fan for venting the room on a thermostat. then have a second fan pull in fresh air, cool your lamps, then vent it back out of the room, without contaminating the air with any odor, so no need to filter. the lamp cooling fan can run continuously while the lights are turned on. I think that method is a good start and should have fewer problems.