airflow in grow tent

I am a little confused about this

If i have an air filter in the space where the plants grow, which filters out with a carbon filter and also other processes of filtering, do i still need to bring in external air from the outside? Or does the filter being inside the grow tent sufficient for air being recycled?

Also if i have an air vent with a carbon filter which inhales air and purifies it and expels it outside the tent, do i still need a second fan that brings in air from the outside in? Or does the fact that the either air filter or carbon filter with air duct fan inhaling air causes enough pressure drop for air to naturally rush into the grow tent through its various holes?

Here is photos of mine. Do u have vacuum issues in tent

.there is my scrubber I draw in air from outside filtered through dust shroom and clean and expel air through vortex fan and phresh filter. And the exhaust offers fresh air to adjacent tent hope this helps

so does that dust shroom suck air in? or blow air out?

also does that post in the first picture show two air vents?

as far as i can see and tell you have one air vent on the left which sucks air out? and one air vent tat blow air in?

its hard to discern without description of what is going on?

can you elaborate on the set up you have

Dust shroom blows out air it gets from outside the home. The phresh filter sucks air. Simple air circulation like cold air return and fan

the air duct and fan that is in the second picture, is that the same air duct and fan that is in the first picture?

is it all one connection? or is the left one that goes around the tent separate to the short one on the right side with dust shroom?

No ok hold on. The fan mounted outside tent blows air into tent at end of duct is dust shroom( filters air since I use fresh air from outside)

next is is gray vortex fan sittin on top of phresh carbon filter. That sucks air from tent cleans it gets sent out of tent in to atmosphere

A intake and exhaust is best. Your intake does not need to to b as powerful as your exhaust but still should b sufficient ( no little computer fan lol ). And you need to draw air in because your plants are using up the co2 in the air and it needs replaced

I never really get why you need a intake fan, I have a exhaust fan that creates negative pressure in the tent, so I know smells can't escape then the air naturally comes in through the seems of the tent, I guess if heat is a major issue you need a intake to replace air flow quick enough to speed up the exhaust fan

Because your working your exhaust fan extra hard making it pull before it can push, and your also loosing a lot of the cfm your exhaust should b doing.

ihave a video clip but cannot get it to post here you have an email ill send you the video

[video=youtube;9TCb2pirjSA]https://www.youtube.com/watch?v=9TCb2pirjSA&feature=youtu.be[/video]
here you go best i can do you will see i use 3 lil 6" fans in for circulation and a small heater as well we have been at -temps here so i need it. I draw in air through dryer vent so it gets fresh air all day no need for expensive co2 crap. I've done just fine temps range from 85-75 day and 75-65 at night. humidity never been over 28% in this room. 1 400w virtual sun HPS 1 large plant and 2 very small others along with a thai pepper plant in rear as well. hope this rambling helps you

I'm thinking my method works quite well but what do i know

candleguy said:

I never really get why you need a intake fan, I have a exhaust fan that creates negative pressure in the tent, so I know smells can't escape then the air naturally comes in through the seems of the tent, I guess if heat is a major issue you need a intake to replace air flow quick enough to speed up the exhaust fan

Click to expand...

You are very correct in your assumption, that when air is sucked out of whatever space/vacuum, then air will rush to fill that space , best example if you get a plastic bottle and suck all the air out of it, you will see how it quickly "inflates" once you release the source of pressure from its opening

And that is exactly what i am thinking, that an extra fan which pushes air in is not really required, because the air pressure on the outside will push air in nevertheless , the same way when you get a straw and suck all the air out of a can of coke, how you feel the air pressure quickly refill it

Atmospheric pressure is 101325 Pascals which is ALOT of force that can move air (m/V) very quickly , alot faster than the force produced from a rotational force that a fan of x rpm can push into some space

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this is how things work in the physical universe

the force from the atmosphere rushes to fill in empty space that is created by the vacuum(the exhaust fan)