Co2 questions

My grow room is 5ft (H) by 5ft by 3ft. I have a baby room above this that is the same size but only 2.5ft (H). I am running a 225cfm fan in the upstairs room. I have about a 8in tube allowing air to travel from downstairs to up. The fresh air comes in from two 4in vents with dryer duct on them but are non-restriced. There is also a 10in fan in downstairs. I rigged up a Co2 (big one) and used a plastic hose to run it into the fresh air dryer duct. 1. there is suction so the Co2 is going in. 2. the Co2 is heavier than air so isn't rising out of the duct. My question is what is stopping the Co2 from being blown out of the room by the exhaust fan? Will this set up work?

you need static room for co2 to be useful. i use cylinders like shown in my gallery to draw air over the lights. the air is pulled from outside and is pumped back outside trying to achive 1500 ppm with fresh air being pulled through is a waste of time

most growers that use co2 only put it in when the fans are off, like at night when the lights are out and heat is no longer an issue.

Ok, so basically the Co2 is really only used during flowering. I have it in there now and I am still in Veg. It's not going to hurt having it in there now though right? I guess not because it is just getting pumped out. Thanks for the help.

You can use it through the whole cycle no issues. Like with me Im in 12/12 so I have a few timers going.Like lets say mu light come on at 10 well my co2 tank is on a timer to first inject the room for 10 til 10:06.My fans are off at this time.Thenat around 11 my fan timers kick on exhaust the room and bring in fresh air.This cycle goes on for the whole 12 hours light on cycle as co2 is only good when lights are on.So my co2 times that the tank turns on are like 10,11:30.1:30,3:30,5:30,7:30,9:30.The co2 satys in for about an hour per cycle then an air change with the fan timers comes on.After 12 hours the timers turn the lights off for 12 hours dark

Ok, then I really should have my fan on a timer also I guess. I am just running a home made Co2 set up so I have no way to controll it. But still if I have my fan run on timer I should be ok. I am a little concerned with heat though. With everything running my room stays at about 82. I think it would soar without the fan. Any thoughts?

You have me confused dude, at one point you say you have a big co2 setup, that you say you have a homemade setup......one point that seems to of been missed is what lighting are you using? (yes it does matter) a temp of 82 with co2 is low.My room regularly hits 90 degrees before I'll exhaust the room.
Peace

I am using a big home made co2 set up. Compared to what I am reading about other home made co2's its huge. As for the lights I am using a four foot eight bulb T5. I've heard mixed reviews from it won't grow a plant over a foot tall to it's better than a 600W HID. I haven't found any confirmed opinions though so I am going to have to learn for myself. This much I know, I grew the plants to over a foot tall with four 40W flo bulbs. Two were grow and two were sunlight spec. I know for a fact that the T5's are going to do better than that. So, I have already proven the fact that they won't grow a plant taller than a foot wrong. I guess I'll just have to wait and see the results. As for temp, I will have to time the fan to kick on when the temp gets higher when I go to 12/12. They are still in veg right now under 24 hr. light.

The T5 light interest me for vegging. I will eventually probably get a few but gonna wait folr cost to come down a little.My co2 setup is a co2 tank with electric solennoid which opens on a timer so it makes it easy for me.My temps stay around 60 with fans off with the 3 400 watt light

T-5's are good, thats about 40k lumens. What I am not sure of, is the validity of using co2 under a low light/low penetration condition like that. I can't remember where I read it, but I do remember something about co2 needing HID lighting. The other side of the coin is that you have a minimum investment into the co2, so try it, see if it helps.
Peace

Thanks for the help everybody. I will keep everyone posted. Hopefully some pics this weekend.