Is there such thing as TOO much air flow?

[Hella THC]

Hey IC Mag!

I'm in the process of constructing a Rubbermaid tub grow. I'm using two 35 gallon tubs instead of the traditional 30 gallon.

I'm going to be pulling through a can style carbon filter that will be located outside of the Rubbermaid (to save space in the grow area, obviously).

My first thought was to purchase an inline style vortex fan but after hearing all the complaints about noise from those things, I've decided to look elsewhere. I then stumbled upon the Whisper line of Panasonic fans from suggestions on this board.

I have been thinking about this one:

http://www.faucetdepot.com/faucetdepot/ProductDetail.asp?Product=16937&AffiliateID=Shopzilla

The thing should get the job done really well! The only thing is, will 120 CFM be TOO much? Or is there such thing? I figure as long as the plants are not getting tossed around too much, it should be fine.

Any thoughts would be great. By the way, the dimensions of my Rubbermaids are (roughly, I'm rounding the numbers for ease): 33" x 20" x 19"

- Hella

 

[DiscoBiscuit]

You'll be fine. If plants blow around more than you like, a speed controller can fix that. S&P is a good brand of less noisy in-line fans. They're not as quiet as some Whisper models but less noisy than a vortex.

EDIT - If I did the math right, that's better than 8 exchanges a minute.

 

[Sam the Caveman]

Once you put your carbon scrubber on it, it will cut the airflow down by about half.

You should be just fine.

 

[Hella THC]

Hey Disco, thanks for stopping by. I really enjoy your advice given in many of these threads. You always seem to have something good or helpful to say.

And Sam, thanks for the info about the carbon scrubber. I wasn't too sure about how much the scrubber would affect the air flow.

Sounds like I'll be going to a local dealer that sells the fans! - Hella

 

[DiscoBiscuit]

Hell yeah Hella, Sam's right. Carbon will slow the air flow down. Some fans whine when they kick in to deliver the same load with a butt load of carbon stoppin' things up. In this case, you may find a happy medium with the speed cont.

 

[masterKahn]

If your plants aren't being damaged by the air flow like leaves tearing it should be fine. The only problem might be quicker evaporation of water in your media.

 

[grow1620]

...also consider the fact that if air is moving quickly through your scrubber, it won't work as efficiently, and it will wear out quicker.

 

[DiscoBiscuit]

they don't work as good in high humidity

 

[Hella THC]

Okay, in reading the reviews of the Whisper line vs, the S&P models, I've opted for the S&P TD-100x http://www.hvacquick.com/spfnconfig.php?fm=td

I brought up earlier the fact that my scrubber is going to be OUTSIDE my box in order to save space for the plants to grow but now I'm curious about something.

I plan on using a can style filter. Do those filters even work outside of your grow area? Or do they need to placed inside?

 

[DiscoBiscuit]

If you want to suck the exhaust air through the filter, it has to be inside the box. I guess you could mount the filter outside but you would have to blow exhaust air into it. The fan doesn't blow through a filter as good as it sucks. On a positive note, some say a scrubber has a muffler affect if air is blowing through. Never tried it though.

If you already have the fan then disregard the rest. A Panasonic Whisper fan could be mounted on top of the grow container. A flat style carbon filter can be mounted in the ceiling of the grow container. This setup would suck through the carbon and work efficiently. There is a tutorial for the wooden frame carbon scrubber that fits the square manifold on the Whisper fan. Which ever way you go, they're both great fans. I think you have to wire the ac cord on each but it's pretty easy.

EDIT: the whisper fan scrubber takes about 2" of vertical space inside the box. I think it could be modified with a 1" tall frame/1" of carbon. You'd only lose an inch that way.

 

[Hella THC]

Good seeing ya again, Disco!

I haven't purchased the fan yet, no, so my options are still open.

I'm hesitant to go with the wood frame/square intake idea, although I like the design and the idea a lot. The fact that ill be running a Rubbermaid box means the lid, or the top box, is going to be removed any time I need access to, or see the plants, which will be daily, and it will be difficult if I have to worry about a carbon filter on the top of it. I know it could be done, but I'd rather avoid it.

I think I'm going to try pushing through the filter directly after the fan. I like the idea of muffling the sound anyway. The CFM will be reduced, sure, but I think I will have MORE than enough air flow with this setup, considering most people cool these boxes with a 120mm PC fan.

Thanks again folks!

Once I get things up and running I'll be starting a grow diary with lots of pics. I don't want to start that thread until I'm all good and ready, but I'm super excited to do so!

- Hella

 

[Hella THC]

Okay, I've been thinking about this for a while now and I think I'm going to use darkroom louvers as intakes for this set up. I have two options in mind. Keep in mind I have one 4" exhaust. My two choices are...

Getting one of these. an 8" x 8" square darkroom louver...
http://www.adorama.com/DKL8.html

or TWO of these, 4" round darkroom louvers...
http://www.builderdepot.com/browse.ihtml?pid=11367&step=5&prodstoreid=301

I'll be using the S&P TD-100x (~139 CFM) fan and I'll be blowing through a 150 CFM carbon filter.

Which intake option would you use? I think the square louver will be too large...

 

[~fvk~]

Get the 8x8 louver, it'll be straight. You'll need 8 round ones to equal 2 4" passive intakes.

 

[Hella THC]

I ordered the 8"x8" louver tonight, as well as the S&P TD-100x inline fan (137 CFM) so I think I'll be ready to start assembling this thing this weekend.

 

[datura_kid]

not to open new thread for this question, which is pretty related:

im doing new setup in new space (20m3 (4mx2mx2,5m) -> with 4m2 plant area). Is it enough to exchange air every 5 min? what is optimum and what is lowest acceptable excange rate?

 

[habeeb]

running higher airflow will have you changing the air filter more, and it's overkill. your choice

 

[habeeb]

not to open new thread for this question, which is pretty related:

im doing new setup in new space (20m3 (4mx2mx2,5m) -> with 4m2 plant area). Is it enough to exchange air every 5 min? what is optimum and what is lowest acceptable excange rate?

I've had closet grows with no air exchange fan, and did just fine if that helps any