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Fans needed for Grow Room

Discussion in 'Grow Room Design/Setup' started by RyanBroo, Jan 12, 2013.

  1. What sort of circulation setup should I use for a 3x3x7 growbox (attaching carbon filter as well)? I figured I needed about 250cfm fan's, So should I get 4 115 cfm fans (2 in, 2 out) or what sort of setup should I use?Or should I have passive intake and a blower fan leading to a carbon filter? Ideas?
  2. #2 bender11, Jan 12, 2013
    Last edited by a moderator: Jan 12, 2013
    I have a flowering cabinet of similar dimensions as yours, utilizing a 400 watt HID. I have a 4" fan/filter/reflector setup at the top of the cabinet. I use the fan to pull air through the filter and then output it through a flange in the roof of the cabinet. For intake I have three passive 2" holes about a foot from the bottom on the back wall of the cabinet. I also use an inline reflector to try and remove some of the heat.

    The tubing in the fan/filter assembly takes care of any light-leaks in the output. For the intake however, I use three 60-degree PVC pipes, painted black on the insides, to trap the light on each intake hole. You can put a flashlight to them in a dark room and see zero light on the other end.

    I use two small fans that rest on the floor and point up to promote better air circulation. I would love to find little metal caged fans like a typical school bus has. I would get two or three of them and mount them to the walls near the bottom, all pointing up and either to the slight right or left.

    Bottom line, one decent exaust fan and passive intake should do the trick. Regardless, you will need a "standard" fan or two on the inside just to promote circulation. Good luck!

  3. #3 RyanBroo, Jan 12, 2013
    Last edited by a moderator: Jan 12, 2013
    Alright, So I've decided that I will use a passive intake with a exhaust fan leading to a carbon filter, with a required 250 Cfm(apprx) how should I do this? Use a big blower fan at the top that leads (Aluminum Ducting) to a carbon filter?

    Would this type of fan be adequate to pull the air into aluminum ducting that leads to a carbon filter?™-inch-inline-fan-435-cfm-p-3802.html
  4. #4 Bongsauce, Jan 12, 2013
    Last edited by a moderator: Jan 12, 2013
    Usually it's better to run it the other way with the filter first, then attach to exhaust fan. If you run it with the fan first, pushing into the filter...make sure to put some prefilter material inside of your filter so that you filter out any dust before it hits the filter. If you don't properly prefilter the incoming air it will dirty up the filter super quick and make it ineffective. Also not properly filtering the air going into the fan will screw up the fan over time as well which is why it's usually recommended to put the filter first. ie, grow>filter>duct>exhaustfan

    Ime it's always better to go overkill and dial it down. I try to always use 'long' style filters because they will last longer and filter better...which is well worth the extra 20$ or so in the long run.

    spot on advice by bender11 btw. :)

    *edit I personally would go with a 6" like that and dial it down with a speed will make a bit of noise though....if you want a stealth fan you can run a panasonic whisper bathroom fan....I've run a few of these and they work great and are dead silent.
  5. Thanks Bongsauce! I have been starting to contribute to this community, although it looks like I may have already given bad advice elsewhere.

    I wanted to also say that I was incorrect when I said I used 60-deg PVC, they are actually 90-deg. Rumpleforeskin has a great pictorial that I probably used as a basis for my design here:*-light-proof-mounting-axial-box-pc-fan.html

    I do not use fans, and I also have the PVC "hug" the side of the walls more to minimize how much the piping takes up. Either way, Rumple's guides are always fantastically written and inspiring, I would definitely check them out if you have not yet RyanBroo.
  6. And thank you both! Does a setup like, a passive intake (using aluminum duct faced down) followed by fans in the grow box which would circulate the air up near the light, then a exhaust fan on the top (Hurricaneâ„¢ 6 inch Inline Fan 435 CFM - Plantlighting Hydroponics) which would push the air (by aluminum ducting again) to a carbon filter ($40.html)? It would be for 5 plants, and that air mover is 400 and something CFM. Does that look like an adequate air design?
  7. umm..sounds good I guess...not sure what filter you plan on using..the link didn't work for the 40$ one ..? It's important not to skimp on the filter too man..if you push too much air through a smaller filter it won't filter the smell.

    You might actually be able to get away with a 4" set up. How many watts are you gonna stick in yer box?
  8. Sorry, it was this filter$40.html . I was thinking of doing a 250watt Hps, then in a few months upgrading to a 400watt. Would that filter cover those plants/airflow?
  9. I can't speak for how that filter will work...I've only used activated carbon granules in my filters...just read thru that thread a bit and see what people have to say about and the fan they're using etc..
  10. Thanks for the advice! Could anyone reading tell me if a 435 hurricane inline fan (exhaust) is enough (or to much) for a 3x3x7 Wooden grow box that has 5 plants in it? And if anyone could recommend a appropriate carbon filter for that size?
  11. I'd get something like a 6" phresh filter.. that's what I use. I go with the long style of filter cuz it's only like 20$ more but you get alot more use out of it. I also highly recommend a speed controller for the fan to be able to adjust temps and noise levels :)
  12. Any diy filters for a 400cfm fan like that?
  13. I made one similar to this one but honestly it's not much more to buy a premade one..the real cost is in the carbon. So if you can get the carbon cheep then it's worth it to make yourself.

    ...the diy filter you linked probably works pretty good....I'm just stating my personal preference :)
  14. I have always bought premade filters. Somethings I absolutely want to DIY, like the Rumple-cloner, but other things like a filter, I don't.

    Illogical I guess, sometimes. I am finishing up an electrical engineering degree and the one guy who knows about my grow keeps trying to get me to make my own custom ballast. I keep telling him that it would probably end up burning my house down! lol.

    That being said, I remember hating all the overhead costs associated with making my first cabinet. So I do see the lure in DIY filters.


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