Correct CFM to scrub tent.

[Johnxnyg]

I like to have my filter on the outside of my tent, so I pull the air through the fan and then blow it out the filter.
(So I have more room in my tent)
I have a tent 30" x 30" x 63".

Will 347cfm fan be enough to scrub that? I am not sure how many times per minute i need to scrub the tent to remove the smell. Thanks guys.

http://growershouse.com/vortex-s-line-6-347-cfm-fan-phresh-400-carbon-filter-package

Is what I ordered. If its not enough... well I will just have to get something else. Thanks!

 

[kcbudluvr]

I'd say that fan is more than enough. Your tent is only about 33 cubic feet. You could get a smaller fan if you wanted to. Or you get a speed controller and turn it all the way down. With that thing on full blast you are basically changing out the air every 5.67 seconds if my math is correct. I've read that 5-6 times per minute is adequate (this figure could be wrong, so double check. I'm going by fuzzy memory).

 

[Johnxnyg]

Lol once I saw my tent was in inches, and not feet I didn't feel like doing all the conversions to figure out what the sq ft was. Not that it was much. What I really was looking for was the 5-6 times per minute number.

5-6 per minute is adequate enough to remove the odor?

 

[DankkAbuser]

I have the same problem i have the same size tent and not sure
weather to get the 190cfm or 440??

 

[Johnxnyg]

Dank I would go with the 440, or the 347 that I am about to purchase. I have a 190 on the tent and a little odor leaks out. Nothing terrible, but I am upgrading for a reason! Hopefully my experience can save you a little money and help you out! I will let you know when i recieve my shipment this week and tell you how it works out!

 

[NorthofEngland]

Equation to calculate suitable inline fan.

1.2 x 1.2 x 2.0 = 2.88m3 (cubic area of tent in metres)
2.88 x 1.25 = 3.6 (25% margin of error)
This is also the amount of air than needs exchanging every minute - 3.6m3
3.6 x 60 = 216m3/hr (minutes x 60 = the amount of cubed metres per hour.

Here is an attachment to the RvK webpage that helps show which size fan is needed:
http://www.hydroponics.co.uk/Ventilation--CO2-and-Environmental/Ventilation-(1)/RVK-In-line-Duct-Fans

As you can see, 216m3/hr is slightly less than the maximum ability of a 5" inline.
Personally I would use a 6" with a fan speed controller.

In my experience it's always better to have more fan than you need,
than to need more fan than you have.

 

[DankkAbuser]

I appreciate that brrotha
i think im gonna go with that 440 just incase

 

[Sunbiz1]

I have the same problem i have the same size tent and not sure
weather to get the 190cfm or 440??

I have a 440 rated for the exact cubic feet of flowering room, and wish I had bought larger.

When it comes to carbon filters, go big or stay home...wanna buy mine?.

It's only 2 months old and I need at least an 800.

PM me if interested.

 

[DankkAbuser]

Would the 440 burnout if i have it turnd down with speed control to below 50% the entire bloom cycle?
I dont need all 440cfms

 

[Johnxnyg]

Equation to calculate suitable inline fan.

1.2 x 1.2 x 2.0 = 2.88m3 (cubic area of tent in metres)
2.88 x 1.25 = 3.6 (25% margin of error)
This is also the amount of air than needs exchanging every minute - 3.6m3
3.6 x 60 = 216m3/hr (minutes x 60 = the amount of cubed metres per hour.

Here is an attachment to the RvK webpage that helps show which size fan is needed:
http://www.hydroponics.co.uk/Ventilation--CO2-and-Environmental/Ventilation-(1)/RVK-In-line-Duct-Fans

As you can see, 216m3/hr is slightly less than the maximum ability of a 5" inline.
Personally I would use a 6" with a fan speed controller.

In my experience it's always better to have more fan than you need,
than to need more fan than you have.

You lost me at meters! Lol jk
I follow your equation until you present the 3.6 x 60.

Is the 60 just represent minutes, and then you are showing it can clean the air per minute? Thank you for breaking it down, I am just not sure what the 60 represents! Thanks!

 

[BallinOnABudget]

You need the filter inside the tent. The fan should suck the smell through the filter then exhaust or it won't work near as well. Room inside the tent doesnt mean much when the feds kick your door in cause someone smells some sticky and reports you.

 

[Johnxnyg]

You need the filter inside the tent. The fan should suck the smell through the filter then exhaust or it won't work near as well. Room inside the tent doesnt mean much when the feds kick your door in cause someone smells some sticky and reports you.

why does the filter need to be inside? I have read the pros and cons of each, yet never read anything where it NEEDS to be inside?

All i I have read that the filters last longer when sucking through them and not pumping out of them. Thanks!

 

[Freedom35]

if its not inside how would it suck the smell or air out of the tent? think about it... you just dont push through a carbon filter that doesnt make sense

 

[Freedom35]

and that fan is wayyyy over kill u wont be able to keep humidity ull suck the air out so fast. u would need a fan speed controller and turn it all the way down which at that point you could have a smaller fan.

 

[WDIK]

No way do you need a 300+ CFM fan for a < 40 CF grow space.

 

[Johnxnyg]

if its not inside how would it suck the smell or air out of the tent? think about it... you just dont push through a carbon filter that doesnt make sense

I am not trying to suck the air out, I am pushing the stinky air through the filter, as long as you have some hvac skills, and no leaks there shouldn't be a problem with this solution should there? I contacted a local a member of the steam fitter union of NYC and he confirmed while it is not as efficient as pulling the air through the filter, it should still work as long as there are no leaks. Anyone else have Ny input!?

Ps . Already have a fan controller and a humidifier so no issues there

 

[WDIK]

What's the reason for pushing air through the filter vs pulling it through?

 

[Johnxnyg]

What's the reason for pushing air through the filter vs pulling it through?

So I have more room in my tent. This way I can put the filter outside the tent and have more room for my babies. My hvac friend said its less effeciant but will still work but you need a stronger fan (to actually push the air through the carbon) and it saves some space.

 

[WDIK]

So I have more room in my tent. This way I can put the filter outside the tent and have more room for my babies. My hvac friend said its less effeciant but will still work but you need a stronger fan (to actually push the air through the carbon) and it saves some space.

I agree it will work with a stronger fan. Like your friend said, it will just be less efficient. I believe there are a number of people out there that "push" through a filter.

I will say that I have a smaller CF tent than you, but about the same height. I have plenty of room even with the filter inside the tent. When I got my filter and looked at it, I thought the same thing. "This is huge". But once I got it mounted (horizontal along the back wall), it's really not in the way.

 

[Johnxnyg]

I agree it will work with a stronger fan. Like your friend said, it will just be less efficient. I believe there are a number of people out there that "push" through a filter.

I will say that I have a smaller CF tent than you, but about the same height. I have plenty of room even with the filter inside the tent. When I got my filter and looked at it, I thought the same thing. "This is huge". But once I got it mounted (horizontal along the back wall), it's really not in the way.

Yeap he said the filter won't last as long (no pre filter) and he said you MIGHT leak some smell out of the actual blower if the filter is not super efficient in passing the air through the carbon, and you have back pressure coming through the fan (highly unlikely) he said.

To to be honest wdik I went from a 2x2 tent to a 3x3 tent, and have not tried putting the filter inside the 3x3 tent. When I receive this shipment this week I'll try putting the filter inside to see how much room I have. Thanks guys!