Passive air intake calculation questions

New guy joe

New guy joe

Member
hello so my rooms are going to be 5'x5'x6'. Running carbon filter through a 6" 400 cfm inline exhaust fan through a/c hood then out of the room.

I plan on having a passive air intake the question is what size does it need to be to still have negative pressure?

8"? 10"? Or 12"
Prefer it to be one of those sizes so I can attach a bug screen. ( fuck those plant eating bastards)

Don't know if this changes things but I will be running co2 in my flowering room.

Thank you for any advice or previous experiences you want to share.

Stay high happy and healthy.
 
New guy joe

New guy joe

Member
Great idea and chart. I will just purchase the 10'' screen and start with a 8 '' hole.

This is my first indoor grow and this forum has been so incredibly helpful!
 
bravedave

bravedave

Well-Known Member
New guy joe said:
hello so my rooms are going to be 5'x5'x6'. Running carbon filter through a 6" 400 cfm inline exhaust fan through a/c hood then out of the room.

I plan on having a passive air intake the question is what size does it need to be to still have negative pressure?

8"? 10"? Or 12"
Prefer it to be one of those sizes so I can attach a bug screen. ( fuck those plant eating bastards)

Don't know if this changes things but I will be running co2 in my flowering room.

Thank you for any advice or previous experiences you want to share.

Stay high happy and healthy.
Click to expand...
One other item you may consider is a variac speed controller for your exhaust fan. Also not sure I follow about the CO2 addition. If the room is not sealed ir seems a waste.
 
New guy joe

New guy joe

Member
bravedave said:
One other item you may consider is a variac speed controller for your exhaust fan. Also not sure I follow about the CO2 addition. If the room is not sealed ir seems a waste.
Click to expand...
I have a variable speed controller and thermostat controller. How would I set up a closed room? I've tried reseaching it but havnt found an understandable set up.

If you could point me in the right direction my flowering room would be forever grateful.
 
New guy joe

New guy joe

Member
Actually I understand what I would need to do but it would consist on me buying a dehumidifier, split a/c and another exhaust fan which atm is not in the budget so I will hold out on co2 until I can afford to upgrade my grow into a sealed room.

Thank you though because it will save me 100$s in controllers, tanks, etc.
 
Antman15

Antman15

Well-Known Member
New guy joe said:
I want to be able to move these rooms into a garage when I move. Most garages have a 7' clearance so to be able to roll one in I would have to keep it around 6'.
Click to expand...
Ok cool....why not just tents then? Most are around 7' and you can pretty well move it anywhere. Just a thought.
 
New guy joe

New guy joe

Member
Tents arnt well insulated and this will be in an area that needs extra insulation. High summer temps and low winter.
Also I can build two rooms for like 175$ - piece
So the price difference isn't to much different.
 
A

adower

Well-Known Member
Your passive intake should be 2x the size of your exhaust. So you need two 6" intakes or one 12".

If you're running a passing intake then no c02. That makes absolutely no sense. Only run c02 if you have a sealed room.
 
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