# air exchange



## that_girl (Oct 28, 2013)

i've read here that ppl have air exchange in the room every 2 sec, forgive me if i'm mistaking...  so does that mean that AC turns off and on on a timer? and so does the filter?


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## The Hemp Goddess (Oct 28, 2013)

No, that isn't quite what that means and I think that you mean every 2 minutes, not every 2 seconds.  It has to do with the exhaust fans (which often run all the time, but always while the lights are on) and not the A/C.  Filters are passive things with no fans--are you talking about an exhaust fan that is connected to a filter? 

What it means when others say they exchange the air once every 2 minutes is that you run an exhaust fan that is moving 1/2 the volume of the air in 1 minute or the entire volume of the room in 2 minutes.  I like to exchange my air more often.  So, a room 4 x 4 x 8 has 128 cu feet. would need a fan that moves at least 64 cubic feet of air a minute to be able to exchange the air in a 128 cu ft room once every 2  minutes.  We always go larger than we need because ducting and bends in the system cut down cfms.  

Did that help?


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## that_girl (Oct 28, 2013)

Yes!!! Thank you, THG!!! 
:doh:it did say 2 min, and i probably even read it in one of your comments.

i had no idea that exhaust is only run with lights on...

yes, mine is connected to the filter. the air goes through the filter, then through the lamps and fan is pulling it out. Everything is connected with ducting..

so i need to set up a timer on the fan, right?

my six inch fan pulls 452 CFM. the dial goes from 1-10, im assuming CF change when i switch the dial...


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## Auburn1985 (Oct 28, 2013)

that_girl said:
			
		

> Yes!!! Thank you, THG!!!
> :doh:it did say 2 min, and i probably even read it in one of your comments.
> 
> i had no idea that exhaust is only run with lights on...
> ...



Many people (including me) run exhaust fans 24 hours per day...even when "asleep", plants are active and can use fresh carbon dioxide (CO2) blowing across their leaves...


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## that_girl (Oct 29, 2013)

thanks , Auburn. if the air is constantly being pulled out how does it work with CO2? it's suppose to be a certain ppm, right?  I never had a burner , want to add it to the next cycle.


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## mikeydean (Oct 29, 2013)

Mine are on 24/7 all the time:hubba:


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## ShOrTbUs (Oct 29, 2013)

that_girl said:
			
		

> thanks , Auburn. if the air is constantly being pulled out how does it work with CO2? it's suppose to be a certain ppm, right?  I never had a burner , want to add it to the next cycle.



you don't run an exhaust fan with c02. there is no need for air exchange, because you are pumping c02 into the room. the reason for air exchange is because depending on where you live. the air around us has roughly 300-350ppm of c02. exchanging the air every 2 mins means that you keep the c02 levels at around 300-350ppms. when you use c02 injection. you want to seal the room, and pump in about 1500ppm of c02 and try to keep it at 1500ppm. you also wan't to raise the temp in the room to about 85F instead of 75F. 

there are many more things you need to differently with c02 and muh more to learn. i suggest getting your current room dialed in before you upgrade.

EDIT: if you're adamant about moving forward. this is a good combo you might want to look into

edit #2: there is also a hydrogen mini. getting the big one is worth it though. in case you ever wan't a larger grow


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## NorCalHal (Oct 29, 2013)

Auburn1985 said:
			
		

> Many people (including me) run exhaust fans 24 hours per day...even when "asleep", plants are active and can use fresh carbon dioxide (CO2) blowing across their leaves...


 
This is false my friend. Plants give off co2 at night, they don't use it.
The only reason to exchange air at night is temp/rh control.


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## ozzydiodude (Oct 29, 2013)

IMO learn the basics of growing before looking at CO2 and the advanced growing techs. Just startng out you should concentrate on lighting, growing medium, venting and getting good genetics to start.


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## The Hemp Goddess (Oct 29, 2013)

NorCalHal said:
			
		

> This is false my friend. Plants give off co2 at night, they don't use it.
> The only reason to exchange air at night is temp/rh control.



I think that was what I was trying to say but didn't elaborate enough,  You need air exchange (if you are not using CO2 enhancement) all the time the lights are on for proper photosynthesis.  Whether you run your fan when lights are off depends on your environment as plants do not need CO2 when not photosynthesising.  I never run it during lights out in the winter for example.  It is hard enough to keep the space warm without exhausting the warm air I have to add.

There is a lot to adding CO2 to your grow--more than just adding the CO2 burner or tank.  You need a sealed room, you need higher temps, and you need enhanced lumens for your plants to be able to utilize the extra CO2.  In addition, the equipment is rather costy.  The CO2 generator or a CO2 tank system is not that much, but the regulators and monitors are expensive.  NCH is quite knowledge on CO2 enhancement.


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## that_girl (Oct 29, 2013)

:cool2: i will do more reading on the CO2 , NorCalHal, u have ant suggestions on the good read on the subject?

and since it's finally cooling down  around here i guess i can turn off the AC during when lights r off. What about the filter and the and the fan (that is getting the air out of the room)? if no air is coming in, nothing should be coming out, right? so from what i understood, i can turn off the AC, the filter and the fan connected to the filter during the day, when lights r off?


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## sunakard2000 (Oct 29, 2013)

with the cooler months comming, well seems to already be here for me, i stopped using my AC about a month ago since my temps stayed around 80-70(lights on-off) and reguardless if im running my AC to keep my temps in check during the summer or not running the AC my exhaust is running while lights are on, and its off while lights are off, the reason to use an AC is to keep temps in the proper ranges, if thats possible due to colder weather theres no need for the AC, but still exhaust the air to keep proper air exchange while the lights are on...
and on the Co2 subject im with THG, you should really wait, if your still having questions about proper exhausting and such you still have alot to learn before diving into Co2 enrichment, there is ALOT more involved, like THG said its not a simple plug and play set up, its expensive and you need to already have a good grasp on your grows, gotta have good genetics and know how far you can push them without added Co2 levels, and its gotta be a well dialed in and smooth running grow, otherwise youll be wasting your time, money and Co2 on plants that cant utilize it to reach their max potential due to not having your plants dialed in to a tee. iv got a friend whos been growing for like 30 years, he always wanted to get into Co2 enrichment and after 10 years he started dabbling with Co2... lets put it this way, hes still having issues from time to time after 20 years of Co2 enriched growing and all of those problems were from not having that particular strain dialed in perfectly. so you should keep up what your doing and perfect your methods until you have pushed everything to the limits already and then possibly get into Co2, 
sorry if it sounds like im trying to steer you away from Co2 at the moment but id hate to see you spend a few thousand dollars on everything and end up with the same or worse results. pushing plants to their absolute max takes alot of knowledge and experience, and most people dont take the plunge into Co2 enrichment until much later in their growing career, after trying lots of different grow methods, nutes, mediums, lights and so on...


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## that_girl (Oct 29, 2013)

not at all, Sunakard.. i really appreciate you taking the time and responding to me..and you prob right , gotta learn how to crawl ,before you walk..


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## NorCalHal (Oct 30, 2013)

here is a good read.

http://www.marijuanapassion.com/forum/showthread.php?t=58680


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## that_girl (Nov 3, 2013)

thanks hun


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