Passive intake vs active

User1534

Active Member
Okay. I'm pretty confused when it comes to this topic specifically because I'm told different things from different sources. I have a 3x3 grow tent and was wondering whether to use PASSIVE or ACTIVE intake. I've been stumbling on this question for a couple days now. I need to know whether to get two exhausts. And if passive then I'm wanting to vent into a 200 square feet room (400W HPS). If I were to do passive how would I set that up in my tent to blow out? Thanks
 

bunnyface

Well-Known Member
well it depends,

depends on what your temps are and if you have adequate air flow. normally having a tent in a room, enough air is drawn in you may not need intake. the vent tho, thats essential. vent it into the roof,another room, anywhere that isn't the room the intake air is coming from. unless you cant then do what you can.

i have intake and outtake, 4inch fan in 5 inch pipe in, 6 inch fan 6 inch pipe out. vent into my roof space, air drawn in from the hall way.

if you did passive it wouldnt be blowing anything out,, if you get me.

worry about the exhast first, if the temps,RH isnt any good, the add an intake fan.
if you dont and you feel growth is too slow,(maybe hard if you don't know what to expect) the add an intake as they cant breath.

also have a fan in the tent to blow air around in there
 

User1534

Active Member
well it depends,

depends on what your temps are and if you have adequate air flow. normally having a tent in a room, enough air is drawn in you may not need intake. the vent tho, thats essential. vent it into the roof,another room, anywhere that isn't the room the intake air is coming from. unless you cant then do what you can.

i have intake and outtake, 4inch fan in 5 inch pipe in, 6 inch fan 6 inch pipe out. vent into my roof space, air drawn in from the hall way.

if you did passive it wouldnt be blowing anything out,, if you get me.

worry about the exhast first, if the temps,RH isnt any good, the add an intake fan.
if you dont and you feel growth is too slow,(maybe hard if you don't know what to expect) the add an intake as they cant breath.

also have a fan in the tent to blow air around in there
Honestly I wouldn’t be able to vent it into another room and I feel it would be a little out of the ordinary to have venting around the house. Are there any other options? I’m thinking that it’s a big enough room and I have a AC vent blowing into it. I keep the house at 74 degrees. I also live in an apartment and trying to do this the most stealthy way. I was thinking of just putting an exhaust but how would I get the air into my tent would it just go through?
 

2Hearts

Well-Known Member
Wait so I need an active? So I need a exhaust and an intake? There’s not enough info online about this
You do not need an intake fan, the air will move by passive firce not active which would involve an intake fan.

You need an outake fan to make that work.

If there is no info then buy a basic kit and do some growing and it should become easier to work.out.
 

User1534

Active Member
No 3x3 grow tent needs active and will be enough passive with any decent extractor at the outake.
What would be the best extractor for a good price? I was going with just an exhaust being a terrabloom 6”
You do not need an intake fan, the air will move by passive firce not active which would involve an intake fan.

You need an outake fan to make that work.

If there is no info then buy a basic kit and do some growing and it should become easier to work.out.
I was just going to do an exhaust being a terrabloom 6”. Would I have to take out the air somehow or does it just go through the tent? I don’t understand that part exactly
 

bunnyface

Well-Known Member
No 3x3 grow tent needs active and will be enough passive with any decent extractor at the outake.
well thats not true, a 3x3 tent in a room, yeah probably not, put that tent in a smaller room or cupboard, i needed an intake on a 3x3 tent in my garage as its kinda damp in that out building and the airflow is terrible.
put a 600w hps in that tent and an active intake would be useful.

so yeah ,most of the time you dont need an active intake, but somtimes the situation requires it.
 

2Hearts

Well-Known Member
work out the cf of your tent then divide your fans cfm by that - most find they exchange the air quite a few times each min and thats actually overkill.

You can just work it out easily. A big tent or room can get dead spots where the air isnt mixing well, intake and fans can solve that. If you get dead spots in a 3x3 buy a bigger extractor, ditch that pc fan.


well thats not true, a 3x3 tent in a room, yeah probably not, put that tent in a smaller room or cupboard, i needed an intake on a 3x3 tent in my garage as its kinda damp in that out building and the airflow is terrible.
put a 600w hps in that tent and an active intake would be useful.

so yeah ,most of the time you dont need an active intake, but somtimes the situation requires it.
 

User1534

Active Member
work out the cf of your tent then divide your fans cfm by that - most find they exchange the air quite a few times each min and thats actually overkill.

You can just work it out easily. A big tent or room can get dead spots where the air isnt mixing well, intake and fans can solve that. If you get dead spots in a 3x3 buy a bigger extractor, ditch that pc fan.
How much of a bigger extractor? Price wise? Can you provide a link for me possibly??
 

2Hearts

Well-Known Member
Any 4-6" ruck ram rhino acinfinity vivo or such will work. A 6" with a variac speed control is a great option but doubles the price. You can just see what everyone uses in each different tent, not a lot of difference.


How much of a bigger extractor? Price wise? Can you provide a link for me possibly??
 

User1534

Active Member
Any 4-6" ruck ram rhino acinfinity vivo or such will work. A 6" with a variac speed control is a great option but doubles the price. You can just see what everyone uses in each different tent, not a lot of difference.
How quiet are the ACinfities though? I am trying to go for the as silent as can get
 

2Hearts

Well-Known Member
No idea, moving air makes noise, google the fan it should have a db rating. A variac will decrease speed noise and thevsounds pitch.

How quiet are the ACinfities though? I am trying to go for the as silent as can get
 

User1534

Active Member
No idea, moving air makes noise, google the fan it should have a db rating. A variac will decrease speed noise and thevsounds pitch.
Says 32 decibels, seems quiet enough for a apartment I would think. I would assume it would sound like air moving rather than a motor anyway
 

2Hearts

Well-Known Member
You get use to the low hum in the background, 32db is very quiet, make sure its the right size for the tent.

Says 32 decibels, seems quiet enough for a apartment I would think. I would assume it would sound like air moving rather than a motor anyway
 

User1534

Active Member
Further proof that this fan would definitely work. It would be good since I only have a 3x3x6, and it’s powerful enough where I wouldn’t be running at anywhere near full capacity. Around 25 cfm with a carbon filter give or take. This runs a lot higher. Thank you for your responses! Saved me a lot of time and helped me ditch that old exhaust. Appreciate it!
 

BrianBuds

Member
well thats not true, a 3x3 tent in a room, yeah probably not, put that tent in a smaller room or cupboard, i needed an intake on a 3x3 tent in my garage as its kinda damp in that out building and the airflow is terrible.
put a 600w hps in that tent and an active intake would be useful.

so yeah ,most of the time you dont need an active intake, but somtimes the situation requires it.
I use a 3x3 in my room and I vent it out my window using a 4" AC Infinity works bloody amazing
 

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