Trying to get negative pressure in rm w/CO2

will a 6" inline fan pull enough air from the light fixture where the glass lays into the frame to keep a small room in negative pressure? i don't see how co2 would work if your bringing in fresh air with an exhaust fan.

I am not sure what yea mean by Bringing in fresh air in with an exhaust. I have designed many grow rooms for people and myself that do include air cool and Co2. The idea is to have a sealed room... Or, If you must and need air cooled, you need to pull the air through the system not push. There is a good reason and if u need I can explain. Im not not eager to type right now, so im logging ha! Just think about this, how do u get a build up of CO2 in a room if it generally takes about 45 mins etc?? Again these numbers dont mean shit since u need dimensions and method of Co2 release. Anwyas, the idea is to keep the room cool enough for co2 to build up!

I think it all depends on the size of the leaks in your system. Adding foil tape where the glass meets the frame can help. You just have to add more co2 to keep up with the leaks. Co2 will also leak through drywall, paint etc.

Good point burr. Good advice! +rep