Can I "blow" out a Carbon filter? Newbie trying vert

eventualist · Jan 14, 2014

Hi!

I have been reading hours and hours over the last month since I got bit by the grow bug.

However, I have a question. I am in a small space, 29" x 32" (inches) and 10 feet height. I am wanting to use my cleaning filter in reverse, so I can use the hose as a heat remover right above the light.

I am also planning on netting the 3 walls in this closet to pin and train the plants (maybe 3, possibly 2) on the wall as a mini sea of green.

Anyway, I did a quick drawing to show you what I mean. Has this been done? I can't find it.

I'm using a 400W HPS Transformer with a ML conversion bulb. Plan on using most of the ML then switch to HPS at the flowering stage.

Anyone have thoughts on this set up? I'm not planning on running the light chain through the vent, just right next to it will work.

My diagram also shows the heat area I think is changed up by doing this method. It's kinda like having a hood vent (cool tube) but doing it vertical w bare bulb.

So I'm wanting to do OPTION B and BLOW the air through the carbon filter. Maybe the heat will break down the carbon filter faster and thats why they don't do it this way?

eventualist · Jan 14, 2014

Ooops, I need to update the art, sorry, that's not 10feet across on the bottom, that's just 32 inches.

OldSSSCGuy · Jan 14, 2014

You should always pull air through a carbon filter, not try top blow through it. Not only will the air resistance increase greatly but you will potentially bake the charcoal in the filter.

Just my opinion...

eventualist · Jan 14, 2014

Yeah, that's what I was figuring, that heat can't be good for it. But maybe with 10 foot ceiling, most of the heat will be up there.

I've been doing the CFM online calculator and I'm almost set on 240 CFM will be plenty to remove the air. Heck, I would do a 120 CFM if I found a decent combo.

I guess this blow idea isn't going to work, and I'll do like everyone else and just set it up like A and go from there.

SirSteely · Jan 14, 2014

Always pull through a charcoal filter. They are designed for one way airflow only . Also depending on the manufacturer it may even blow out all the fine particles of charcoal causing a mess above your grow. Imagine that dust in your flowers. Having it at the top pulling the heat out will work pretty good. 150cfm or better imo. Best of luck .

qupee · Jan 14, 2014

FUD. Filters work just fine blowing through them. Any difference in resistance to airflow is small, almost certainly inconsequential.

Just use some common sense and consider exactly how a carbon filter operates and what the difference are between sucking through one and blowing through one, and ask yourself how that would affect the filter's operation.

They are not complicated devices. Put air in contact with carbon and over time the carbon traps the smelly organic compounds in the air. Increasing time in contact with the carbon or surface area of carbon being contacted increases effectiveness. Pushing vs. pulling doesn't change time in contact or surface area in contact, assuming a fairly uniform bed of carbon and air flow within a range of reasonable rates for the size of the filter. Heat? The carbon is not different between the outer and inner layers, it doesn't not matter which gets the only very, very slightly warmer air. Carbon dust? Do you prefer it to get sucked into your venting, fan, and maybe light hood or blown out into the prefilter and/or room. No prefilter on the inside when blowing into the filter and worried other dust etc. will clog it. Unlikely, but it's not difficult to put a simple particulate filter somewhere before the air enters the carbon filter if you like.

Somebody once said it's better to pull than push and now it's gospel repeated ad nauseum yet no one can expound on exactly why or how. BS. I've run a number of filters both ways.

Budsworth · Jan 14, 2014

I have several friends that do this to no detriment.

ladera · Jan 14, 2014

I run both my carbon filter and exhaust fan outside the tent and blow through the carbon filter , no probs at all..
I have dust filters fixed to air intake and air out to pick up the dust that
would otherwise quickly clog up the inside of the carbon filter..just need to
keep an eye on the dust filters and clean as required....

eventualist · Jan 14, 2014

ahhh so there are some "Reversers" out there! I've been researching the right combo fan, etc and it would make a difference.

I'm thinking just a small 4" carbon filter can thats barely 9" inches long, out side of a 190 CFM 4" vent tube. not much to it. This is a 8foot x 3 foot x 10 foot high room. It doesnt' take much to change out all the air in 1 min (240 CFM) and 1 time every 5 min is like 50 CFM. I could almost get away w a computer fan! However, I'm realizing a few things about fans. They can be noisy, and the fans can be made cheap (not sealed or lubbed well) and the cheap controllers for speed can break a cheap fan pretty quick.

I just thought if I could put the fan outside of the room and only have the vent tube down right above the vert light, there is very little heat concerns. If i need more heat, I can easily move the intake hose away from the light to build the room up w heat.

Maybe Im' over thinking all of this. The deal is, the closet is more stealth w/o this thing poking up there at the top. So I guess if stealth was big, I would just install a 180 CFM bathroom fan and put a carbon filter on it. I saw the DYI, it looks easy.

Hard to really care about stealth, cause once the door is open, it's all there. Air filter at top of ceiling is probably not such a big deal LOL

NeWcS · Jan 16, 2014

Like QP said...

I have done this and it works just fine.

amannamedtruth · Jan 16, 2014

It will work just fine. If you can, put a pre-filter over the intake of the ventilation. This will act like the pre-filter sleeve on the outside of the charcoal filter. After prolonged use fine particles will clog up the charcoal filter if you use it this reverse way. For your size, try using a shopvac filter from Home Depot, they are designed for high airflow...this will prolong the life of the filter, and fan, quite a bit.

eventualist · Jan 16, 2014

Oh good idea, I didn't think of the shop vac filter as a pre filter! I will do that!

Thanks!

AshitMyself · Jan 16, 2014

I have been blowing through a carbon filter for years now with no problems at all my rhino filter is 3 years old still works fine

Dank Demon · Jan 16, 2014

Both ways sucking or blowing work equally as well as each other with no difference what so ever, and the air sucked or blown through it is the same temperature so will not bake the carbon either way.

Peace

toastfighter2 · Jan 16, 2014

y can filter came with directions on how to hook it up in both configurations, and so far I have used it both ways. At first it was in my flowering room, being sucked though, but it took up too much space that way, so now it is being blown through in a completely different room. My recommendation is that no matter what, you want to run it outside for a few with the fan either blowing or sucking to get rid of the excess dust they have in them, you plants will thank you

Granger2 · Jan 16, 2014

http://canfilters.com/faq.html

Can and other mfgrs say that if you're going to run the filter in reverse, put the prefilter inside. Good luck. -granger

eventualist · Jan 17, 2014

Thanks for the can filter link! I was reading the FAQ and it said:

Is it recommended to push or pull through the filter? It is recommended to pull air through the filter, the reason for this is because the filters utilize the most surface area of carbon to clean the air and you use the most of the pre filter to block dirt and debris from entering your carbon pore structure. Another advantage of pulling air through the filter is that your going to have clean air running through your fan instead of air possibly laden with VOC’s, dust, and other airborne particles that could stick to the fan blades and create air resistance.

chowdan · Jan 17, 2014

I run with my fan pushing air to the filter rather than pulling through. I am running with a 400w HPS/MH in a hood.

I run a 470CFM LEDWholesaler filter and have never had an issue with odors. It was ~$90 compaired to the Canfilter 66 model.

I run with the prefilter on it primarily to stop the smaller carbon particles from falling out.

The main reason i chose LEDWHolesalers over CanFilters/Phresh was due to the cost. I could purchase 2 470CFM filters from LEDWholesalers for the cost of a Can 66.

Another reason i went for them was due to the fact that i am an aquarium owner and purchasing carbon for the filters from places like petco thats a name brand is quiet expensive. I often order bulk carbon for the tanks which saves money. I went for the cheaper model due to the fact that i have plans on tearing it down and trying to replace the carbon when it starts to not be effective.

I only run the filter when flowering, so this saves the life of it(i believe). I'm a week from finishing my second run with this filter and have yet had any odor issues.

The GF gets quiet pleased when i hook up the filter as this completely stops all odors and since our grow is located in our laundry room which is connected to our bedroom in our 1bd apartment.

Hope this helps!

Bush Dr · Jan 22, 2014

This is why I don't bother posting ..... explain using very simple maths and nobody can understand

qupee · Jan 22, 2014

Bush Dr said:
No .... it was designed to suck air, why else is there a replaceable sock?

The diameter of the inner tube is about 4" less than the outer therefore based on a 4" pipe, then that's a surface area of 1/4 of the outer ..... the ratio changes with size

To be precise a 6" Rhino used the wrong way presents 28.8 sq inches per linear inch as opposed to 78.6 which it was designed for ....... based on a 30" long unit that's 864 vs 2356 sq in

Put t the wrong way round and you'll be

1 Putting extra load on the fan, thereby reducing its life
2 Wasting electricity because of the fan working outside its design parameters
3 Reducing the efficiency of the filter
4 Reducing the useful life of the filter dramatically .... don't bother taking it back, if the inside is dirty there's only one reason

It's not just the area of the one surface where air enters that matters, the air contacts the surface of carbon all the way through the bed. When blowing through, the air will still push and spread out through all the various channels (reasonable approximation) contacting as much total surface area on it's way through as when pulling. Similarly, when pulling, the fan has to pull the air from a larger surface area down through a smaller surface area. That presents the same impediment (again, reasonable approximation) to air flow as pushing through the smaller surface area. The surface area of the opening isn't even very relevant, the area of the 6" pipe is only 28.26 sq in, a 30x reduction from the inner surface of your example filter. But that's irrelevant. The surface is mostly blocked by pieces of carbon and air only travels through the channels between them.

Can I "blow" out a Carbon filter? Newbie trying vert

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