# Carbon filter/fan/cooltube/exhaust fan?



## hero4u2b (Sep 6, 2011)

Hi everyone.. In setting up this flowering room.. I know many of you guys run your inline fan after your light or lights and pull the air thru and out to w/e. In reading the instructions and thinking ( ooh no) I am leaning torwords starting with my filter then a short piece of flex. then the 424 fan then another flex and/or 45 galv elbow then thru the cooltube.. out another flex and possibly duct elbow or transision and out to the extractor fan. out of the closet.. I do have a passive intake setup.. My question is wouldnt it be more effecient to pull directly from the carbon filter with the fan and then blow out of everything? blowing thru the cooltube? verse's suckng from behind the cooltube?  Thanks  Hero


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## bho_expertz (Sep 6, 2011)

Blowing tru is not the way. You need to pull air. The instructions aren't lying to you . and the extract fan works to extract air not to blow air ( she does that also ).

I don't have a 424 fan. The extractor does the job well. You just need to get a bigger extractor then the space you have.


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## hero4u2b (Sep 6, 2011)

I beleive you BHO.. I know you guys.. veteran growers .know and have done your homework on this stuff.. I am just wondering why the instructions that came with this fan/filter combo from HTG say to do it like that.. I am wondering the reasoning they say to do it this way verse's the way most everyone here does it.. Thanks Hero  Here is the link to what it is a purchased hxxp://www.htgsupply.com/Product-GrowBright-6in-Tall-Boy-Inline-Fan-&-Charcoal-Filter-Combo.asp


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## bho_expertz (Sep 6, 2011)

The pic in that link is the way to do it. Except with cooltube where it is carbonfilter -> cooltube -> extractor/fan. The fan is nice 424cfm :aok:


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## hero4u2b (Sep 7, 2011)

Ok Thanks BHO


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## Stoneage (Sep 7, 2011)

I was talking to my hydro guy today, and I was looking at getting some new air cooled hoods. He said that I should be pushing through the lights. carbonfilter, fan, lights, then exhaust out.


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## Stoneage (Sep 8, 2011)

Thanks Pfnugs. That was my thought as well. I like to hear that. The way he was telling me, I would have to redo, all my ducting, and rethink of how to turn things around.


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## The Hemp Goddess (Sep 8, 2011)

Actually, I have to disagree--it is not the same.  You want negative pressure in your space--this is a huge part of keeping smells contained.  If you are pushing air through the light, you are not getting this.


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## Stoneage (Sep 8, 2011)

Thanks HG. I have my Filter, Fan blowing out, giving me negative pressure. I thought it was a little strange that was what the hydro guy told me. I just want to get it right b4 I have to start moving things around.


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## hero4u2b (Sep 13, 2011)

Thanks everyone.. My pc crashed and had to buy a new one. My flower room is SET and looks pretty profesional for a guy like me. lol. I am pulling the air thru the light and filter.. Just had wondered why the instructions said different.  Now I have to tweak a few things like dropping veg lights off to the side and so on but Thanks everyone for the help. Hero


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## buddogmutt (Sep 15, 2011)

here's how i got mine setup..and works great...Hemp goddess, i see you refer to "negative pressure" pretty often,and you obviously know your bizz..what is it and how is it obtained...


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## bho_expertz (Sep 15, 2011)

buddogmutt you know your stuff regarding LST but you have the extraction setup wrong. You need to attach the carbon filter inside the tent before the light. If you do this and if your fan is powerfull enough ( i think that you have a 4x4 that is less then 275m3 and usually the fans of 125mm are bigger then that ) you will have negative pressure. :aok:


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## Hushpuppy (Sep 15, 2011)

Negative pressure is the same as vacuum. If you have a given air space that has more air being pulled out than is coming into the room then there will constantly be a vacuum within the room that is pulling air into the room. That is negative pressure, and no smells will get out except through the fan because any openings that might occur within the room will be pulling air in.... 

There is one problem with your (BDM) setup. It isn't automatically a problem but there is positive pressure between the fan and the filter because the fan is pushing while the filter is a resistance to that push, if the hose between the fan and the filter becomes damaged or gets disconnected then your air will no longer be fully filtered. 

I have had that happen several times because I have mine setup backwards and haven't had the chance to move it yet. The positive pressure on the hose causes any weaknesses to show up eventually. That is why it is best to have the filter at the beginning of the whole assembly.


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## HemperFi (Oct 1, 2011)

Filters are designed to have air pulled thru them. That is why they have a pre-filter wrapped around them -- it picks up big dust particles before they go into the filter. Blowing air through the filter isn't the way it was designed to work. *Filter * duct * light * fan * and out. I'm sure of this.


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## HemperFi (Oct 1, 2011)

you can put the fan outsife sucking -- that is okay -- filter -- duct -- light -- duct -- to fan sucking the air out of the tent.


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