Active vs Passive

[420forme]

I'm constructing a new grow box(3x3x4) and wanted to know if it is better to use passive vents with a exhaust system and create a vaccum, or use active (fan assisted) intakes along with the exhaust?
I only have a 4inch 170cfm inline duct fan for exhaust pulling though a filter and hood I can add a couple of 4inch cpu fans (60cfm) at the bottom blowing air in, or just cut vents for fresh air. What do you experienced people do?

 

[W Dragon]

I'm constructing a new grow box(3x3x4) and wanted to know if it is better to use passive vents with a exhaust system and create a vaccum, or use active (fan assisted) intakes along with the exhaust?
I only have a 4inch 170cfm inline duct fan for exhaust pulling though a filter and hood I can add a couple of 4inch cpu fans (60cfm) at the bottom blowing air in, or just cut vents for fresh air. What do you experienced people do?

alright mate i'm on my first grow so no pro, i have both i'm growing in a tent and have 1 large rectangular vent on 2 sides and bathroom exhaust drawing air in can't remember the cfm but it is smaller than my exhaust to create the vacume effect (negative pressure) i leave the intake on 24/7 and block the vents from the outside during lights out this guarantees me plenty of fresh air, i suppose it depends on what you plan to use it for if you plan on strictly vegging in it on 24/7 lights on you could just go passive as you won't need it to be light proof any thing else i would go with both fan and passive. just my opinion mate hope it helps

 

[420forme]

alright mate i'm on my first grow so no pro, i have both i'm growing in a tent and have 1 large rectangular vent on 2 sides and bathroom exhaust drawing air in can't remember the cfm but it is smaller than my exhaust to create the vacume effect (negative pressure) i leave the intake on 24/7 and block the vents from the outside during lights out this guarantees me plenty of fresh air, i suppose it depends on what you plan to use it for if you plan on strictly vegging in it on 24/7 lights on you could just go passive as you won't need it to be light proof any thing else i would go with both fan and passive. just my opinion mate hope it helps

Thanks for your info, the more the better. I plan on using this setup of veg, and flower so the cycles will be changing. I currently run my intake fans 24.7 and just exhaust with the light cycle. Just want to make it very efficient on this new box.

 

[CLOSETGROWTH]

Thanks for your info, the more the better. I plan on using this setup of veg, and flower so the cycles will be changing. I currently run my intake fans 24.7 and just exhaust with the light cycle. Just want to make it very efficient on this new box.

I like the passive intake much better..

You want your exhaust fan pulling the air through, and not just a whirlwind that is often caused by using an active intake fan.

 

[IAm5toned]

passive.


active only works on a pressurized ducting system.

 

[420forme]

passive.


active only works on a pressurized ducting system.

Well sounds like ill go passive, and just add a fan inside for circulation. Thanks for the replys!