Fresh Air in the grow room?

Would not having a constant flow of fresh air into the grow room negatively affect the plants? I run an a/c and I just don't want to pull hot air in my room if i don't need too. any advice would be great! thanks.

plants need to breath

they suck in c02 and gas out 02

replacing that air brings in new c02

best to suck air in from around the house passive like

and extract with a 6 inch bathroom type fan

as a plus it helps the grower get rid of the stink!

good luck

If your room is sealed well enough, then another option is to run CO2. Without a constant flow of fresh air, the plants need to have CO2 to breathe or they'll die.

If you can't run a fan for some reason, getting a CO2 generator is an absolute must. The bonus about CO2 is that you can go higher than the required 300-400 ppm, but only if your grow is optimized for that. Running a sealed room also prevents odor leaks and provides significantly easier control over the room as opposed to fans. A sealed room would cost more to maintain each month, but is capable of far better results.

Your only other option is an inline fan, and the air would have to be run outside. Not only do you need the fan to intake new fresh air, but it also needs to exhaust the hot and used air out. If you're simply exhausting the heat into the same room your grow is in, your room will still be hot. You'd at least have constant fresh air this way, but you'd be running your air conditioner way more because of the heat being inside of your room and not outside the house.

I agree on adding the CO2 also.

If this grow is in or near a living area just be aware that CO2 is heavier than air and a suffocation hazard could exist for humans if sleeping on or at floor level. I may be a little paranoid but the thought did cross my mind.

You need an exhaust fan that exchanges the air every 5 mins on average. Plants need carbon dioxide to live.

Then i suppose the best thing do is vent air out and bring new air in , then have the fans be off at night

jswett1100 said:

Then i suppose the best thing do is vent air out and bring new air in , then have the fans be off at night

Click to expand...

Keep fans going 24/7

A commercial sealed grow chamber exchanges the volume of air every four times an hour and multiple papers present the conclusion that constant air flow stunts plants.

Its not air exchange you need but Co2, a sealed chamber can be exhausted of waste oxygen and topped up with Co2 to give no air exchange whatsoever but enough C02 for normal growth.

Our problem is heat and we use air exchange to reduce temperature, with the right temperature you need very little air exchange (about enough to keep Co2 levels at norm for growth).

So yes you can grow with hardly any air exchange as long as you dont deplete Co2, many growers manage without ventilation and fans in bigger rooms that dont heat up.

*BUDS said:

You need an exhaust fan that exchanges the air every 5 mins on average. Plants need carbon dioxide to live.

Click to expand...

HORSE SHIT! Need Co2 = yes.

See the above post! Room size and plant count/size are the keys. Turn my bloom room over every 1.5 hrs. Have NO problems. Been doing it as little as possible for decades. I do have a Co2 monitor and have never have seen it drop below ambient! So I have a small neg pressure situation also.....

My tent never seems to drop below 400ppm co2 without any supplementation. Sometimes it's up at 600 on it's own. I have a tank with a regulator but I've only been using it in bloom this go around and have had no negative effect.

Try growing without getting the girls fresh air or without any air exchange.

Theyll be fine for about 3 weeks or so.
Then you will begin to see brown spots on the leaves. No problem...just some brown spots, right?
Wrong. The brown spots will get bigger and you will get the sense something is wrong. The sides of the fan leaves will start to crisp up too.
Then youll come here looking for help. People will ask you about pH, and salt build up, nute burn. And youll run around in cirlces trying figure out and remedy the problem.
And at the end of it you will realize...just need to give the girls some fresh air.

Ask me how i know?

And since that experience i have seen many others on this site follow the same stupid path.

Gquebed said:

Try growing without getting the girls fresh air or without any air exchange.

Theyll be fine for about 3 weeks or so.
Then you will begin to see brown spots on the leaves. No problem...just some brown spots, right?
Wrong. The brown spots will get bigger and you will get the sense something is wrong. The sides of the fan leaves will start to crisp up too.
Then youll come here looking for help. People will ask you about pH, and salt build up, nute burn. And youll run around in cirlces trying figure out and remedy the problem.
And at the end of it you will realize...just need to give the girls some fresh air.

Ask me how i know?

And since that experience i have seen many others on this site follow the same stupid path.

Click to expand...

What do you consider less than acceptable ppms co2 in a grow environment?

Dudemankidson said:

What do you consider less than acceptable ppms co2 in a grow environment?

Click to expand...

Average outside is 350 to 400. I guess lower than that....

Gquebed said:

Try growing without getting the girls fresh air or without any air exchange.

Theyll be fine for about 3 weeks or so.
Then you will begin to see brown spots on the leaves. No problem...just some brown spots, right?
Wrong. The brown spots will get bigger and you will get the sense something is wrong. The sides of the fan leaves will start to crisp up too.
Then youll come here looking for help. People will ask you about pH, and salt build up, nute burn. And youll run around in cirlces trying figure out and remedy the problem.
And at the end of it you will realize...just need to give the girls some fresh air.

Ask me how i know?

And since that experience i have seen many others on this site follow the same stupid path.

Click to expand...

Thanks so much for the comment that makes sense.

Currently I just used a tarp and sectioned of the top of the room from where the lights hang off up. just using duct tape to seal the seams, i did this because i figured making the room smaller would make it more managable. and it didnt make sense having all the extra top room while using an a/c. I have the carbon filter above the plants venting outside. temps arent bad especially with 2 600w hps's going in a small area like that.

Gquebed said:

Try growing without getting the girls fresh air or without any air exchange.

Theyll be fine for about 3 weeks or so.
Then you will begin to see brown spots on the leaves. No problem...just some brown spots, right?
Wrong. The brown spots will get bigger and you will get the sense something is wrong. The sides of the fan leaves will start to crisp up too.
Then youll come here looking for help. People will ask you about pH, and salt build up, nute burn. And youll run around in cirlces trying figure out and remedy the problem.
And at the end of it you will realize...just need to give the girls some fresh air.

Ask me how i know?

And since that experience i have seen many others on this site follow the same stupid path.

Click to expand...

I know this is very old but was just wondering about this! Did you have that problem and then you sorted out the circulation and ended up ok?

Dr. Who said:

HORSE SHIT! Need Co2 = yes.

See the above post! Room size and plant count/size are the keys. Turn my bloom room over every 1.5 hrs. Have NO problems. Been doing it as little as possible for decades. I do have a Co2 monitor and have never have seen it drop below ambient! So I have a small neg pressure situation also.....

Click to expand...

Agreed. Sometimes my temp/humidity controlled fan doesn't run at all, but no issues with co2 dropping. Almost never below 500 ppm in the tent, and that's in small, closed lung room.