Ok so I have a 5x9 grow tent and think of adding a co2 tank. What I'm trying to figure out is the perfect ventilation situation. My idea was having 2 inline fans- one cooling off the hoods with no contact with air in the tent for when lights are on, vents are sealed no intake... when lights are off I have a carbon filter>to 2nd fan> out the tent, id also have the vents to tent open at this point for a passive air intake. Does this sound right?
Nope! Not good. The problem being is that you will have NO lights on air exchange at ANY time to relieve the heat/humidity build up! Snaps is close and just missed the heat issue. This would become a HUGE issue very quickly!!!!!
You need an environmental controller. This one is great.
http://4hydroponics.com/autopilot-digital-environmental-controller
You plug in the gas regulator and the exhaust fan. You set your high temp limit and the the high humidity limit. You set the gassing time and the time limit for between gassing and, VIOLA, the gas,humidity and the all important temp is controlled with no extra work for you.
Now of course your going to need a regulator (able to be set for your space of aprox. 315 cubic feet) ,tubing and timer. Here's the perfect kit for your needs as the 10 cfh will shorten the gas on time to more realistic levels.
http://4hydroponics.com/hydrofarm-co2-injection-kit-1-10-cfh
I strongly suggest you use a 50lb tank and skip the 25's for longevity and overall price effectiveness.
Do NOT gas during the LAST 2 WEEKS OF FLOWER! (The use of Co2 will inhibit the ethylene gas from ripening your crop in a timely manor! So no gas the last 2 weeks of flower!!!!)
315 cf of grow space. x .0013 (target of 1300 ppm) = .4095 cf of gas to to reach the 1300ppm in the room.
.4095 cf of gas / (divided by) 10 (cf of gas flow per hr with the regulator) = .04095
.04095 x 60 (min in an hr) = 2.457 min of ON time for the gas to reach the target ppm.
10 min of off time between gassing.
85 deg F high temp setting.
60% high humidity setting.
These are the settings you would feed into the Environmental controller.
I would run my gas line directly into a fan in the tent for airflow and gas distribution.
There you go....
good Luck!
