# Stupid Question-- About Air



## MrPicklesCC (Mar 23, 2021)

Alrighty, so this may be extremely stupid but I feel like I am missing something. 

I am using a 3x3 Grow Tent that has a Vent on the back that can be Covered and Uncovered... Is it recommended to always leave this open? Is that how you get your air exchange? I was worried about having it open during Dark Periods.  

I will have 1 or 2 oscillating fans inside my Grow Tent but I didnt know if I needed to have a port open and have a fan specifically blowing in outside air.

So I guess the 2 big questions here are 1) When to cover and uncover the Ventilation Port on the back of the Tent (the rectangle port) 2) During "Dark Periods," does the Vent need covered? (im guessing so since some light might get in) and if so then how does AIR get in during this time?

I have a 4'' Inline Fan connected to a carbon scrubber that is sucking air OUT of the tent, but nothing that is specifically bringing in fresh air.

Comments, Feedback

Thanks in Advance.


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## yooper420 (Mar 23, 2021)

All i've ever used was an exhaust fan with passive inlets. Worked great for the last 9 years.


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## ROSTERMAN (Mar 23, 2021)

Those should be one way flaps
Air goes in the flaps open when air stops the flaps should close.


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## WeedHopper (Mar 24, 2021)

Never used a tent but my grow room had a vent i made that light couldn't pass thru because of the way i built it. My exhaust fan was in the attic and pulled fresh air in thru my grow room and the stale air out thru a carbon filter. I built my vent where you couldn't look directly thru it and painted the inside black to keep light from reflecting off the walls of the vent. I had negative air pressure in my grow room to a point where the door wouldn't open easy.
The walls of my grow room were made of RMax. It even has white reflective interior walls because of the Rmax.





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## MrPicklesCC (Mar 24, 2021)

Haha, I am a little worried about the negative pressure myself but the tent frame is very solid and strong so I guess we shall see. I am hoping to get everything assembled Thursday or Friday (I ordered 2 extra support bars for the top of the Tent so that has caused a short delay) and then run some "Test Runs," after that with the Light and Fan's on just to see what kind of conditions I am working with. I figure I can read everything in the world but a lot of this is going to be Trial and Error and just seeing what conditions I am specifically dealing with inside my tent.


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## electricPuha (Mar 28, 2021)

My tent is hard up against wall so tent wall flexes so no light gets in vent but enough air comes in.


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## BigJer (Apr 5, 2021)

Plants like fresh air


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## Andrew (Apr 28, 2021)

MrPicklesCC said:


> Alrighty, so this may be extremely stupid but I feel like I am missing something.
> 
> I am using a 3x3 Grow Tent that has a Vent on the back that can be Covered and Uncovered... Is it recommended to always leave this open? Is that how you get your air exchange? I was worried about having it open during Dark Periods.
> 
> ...


You need some ducking to put in vent hole then make a bend in it so no light for dark period


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## BigJer (Apr 29, 2021)

Just use a piece of ducting and and make one loop on the outside and Bam no light.


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## Flushitbro (May 13, 2021)

There are plenty of black carbon filters on the market (try a fish store: filter media, I think it is called) that could be rigged around that area to block out light and still allow air to pass (I think I'm picturing this correctly, but not sure).  In general though, you most definitely need outside air for two reasons 1) too much humidity can build up 2) not enough humidity (potentially) can enter. 

When an exhaust fan turns on it actually does pull in new air from around the outside of the enclosure while it filters out the stale air.  So for example, if you had a humidifier set up outside of your tent and you suddenly cranked it while the exhaust fan is running...over the next several minutes you would see the humidity inside slowly start to rise.  Theoretically, you could just leave the fan going constantly while controlling the humidity around and outside of the tent, and find a black mesh material to cover the outside part to keep light out during night cycle.  

Personally, I have two regular fans blowing over the canopy top, and my passive exhaust shuts off completely 5 times a day for about 1.5 hours before turning back on.  Everything is on timers, Co2 fills the room immediately when the exhaust goes off and if it drops below 2000 ppm in that exhaust free interval, more C02 goes in.  From trial and error, I've learned that you CANNOT HAVE MORE THAN 1.5 HOURS WITHOUT EXHAUST WITHOUT ADVERSE EFFECTS.  Plants need fresh oxygen almost constantly, so if the air around your tent is fresh, the plant will be happy.  Sometimes, I even open the window in my basement to let truly fresh oxygen come in and circulate.  It really does make a difference.


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## BigJer (May 13, 2021)

Wasting CO2, plants can only absorb around 1300PPM.


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## Flushitbro (May 13, 2021)

There are people who would disagree with you on that.  I've heard of people going as high as 5000, but I've never been a plant, so it is tough to say what one actually absorbs (meaning, I would rather go high, as long as it isn't hurting them).

But I actually agree with you...you caught me.  I'm trying to get this canister empty before the July heat makes it explode in my basement.


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## BigJer (May 14, 2021)

Flushitbro said:


> There are people who would disagree with you on that.  I've heard of people going as high as 5000, but I've never been a plant, so it is tough to say what one actually absorbs (meaning, I would rather go high, as long as it isn't hurting them).
> 
> But I actually agree with you...you caught me.  I'm trying to get this canister empty before the July heat makes it explode in my basement.


I know they would but I got my info from an actual real botanist.  ( sassy I know) I got  to sit through a seminar in Bar Harbor and when it was done I got to ask him a bunch of questions and that was one of them. He laughed at me and just said you pot growers but he explained photosynthesis and said it is the same for everything and it's 400-1350.


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