A Filter For My Passive Intake?

jawnroot · Aug 1, 2008

I'm looking for some kind of material/filter to put over my passive intake. It must prevent light from getting in, and prevent smells from getting out, and it should not restrict airflow to any great extent.

Ideas?

PS: Butterfly dampers are out of the question because of the clanging noises. They also restrict airflow much more than most would think.

EatShitake · Aug 1, 2008

Well, you can get darkroom louvers for the light issue. If it's an intake, you shouldn't need to worry about smells...you DO have an exhaust making negative pressure in your space?

You can also use something like an odor sock. They're like disposable carbon scrubbers.

jawnroot · Aug 1, 2008

Yes, I do have an exhaust fan creating negative pressure, but what about when the lights are off and it's not running? That's what I'm concerned about. (Running the exhaust fan 24/7 is not an option, and I never do that anyhow).

I'm trying to find something that can be purchased for a relatively low price at the hardware store. I was thinking one of those carbon or hepa filters, but I'm not sure. Again, all it has to do is prevent light from getting in, and prevent odors from escaping.

CDM · Aug 1, 2008

You should always have your exhaust running regardless of lights. this is what keeps odor out.. if a cloth can let air in, its gonna let odor out if not under negitive pressure

dapimmel · Aug 1, 2008

Get a carbon filter fom a car. Most highline vehicle like Jaguar have them. Not to much money either.

smokeymacpot · Aug 1, 2008

the best you can use is the filter from a kitchen extractor. but like cdm said, fans should run all the time. if they arent, then you should not be restricting vents, humidity, risk of mould e.t.c
you can even run a smaller fan as an exhaust for night time, i helped with a guide in the micro forums for pc fans, so i suggest you go read it and come up with somthing...

Bumble Buddy · Aug 1, 2008

I made some flaps from black/white poly sheeting; taped them to the inside of the passive intakes and weighted them by taping a couple rolls of pennies at the bottom of each one. A similar flap could be made of cardboard or fiberboard or similar. I put some air filters in each intake as well (cheap prefilter and HEPA filter), cut them to size and keep them pressed with a metal vent cover into a frame attached inside the intake made of of 3/4"x3/4" wood with weatherstripping foam on them.

jawnroot · Aug 2, 2008

I have enough growing experience to know that fans DO NOT need to be running all the time. Yes, you do need a fan running inside the room at all times to move air, but turbine extraction fans do not need to be running all the time, contrary to what you've heard. In an ideal world, yes, they would run all the time. But I don't live in an ideal world, and I can't run them all the time.

To the guy who said "if the cloth will let air in...." It will only let air into the cab if the inside of the cab is under negative pressure. With the fan off, there will be no negative pressure. The odor is not going to force its way through the layers of a filter. Indeed, that's the purposes of HEPA and carbon filters to begin with...they're called "forced air" filters for a reason.

I had my eye on those car cabin filters. I'm probably going to get one of them, cut a hole in the wall, and glue the filter over the hole. I can't see any way that odors will get through with that on the end, and I also can't see how light would get through. Done deal.

vespers · Aug 2, 2008

Let us know how it works out.

bigd21 · Aug 2, 2008

I personally use those mask they sale for painting etc.... they are like 5 for $2 and they are designed to filter air, and the ones I have dont let any light in or out

sativa_cyborg13 · Aug 2, 2008

i am a new grower and still working on my cabinet. for my intake on the bottom of the cabinet(9 cubic feet), i was thinking about just cutting holes and running a 4 in fan through a carbon scrubber near the top of the cabinet. is that a bad idea? there is a 2 in. space underneath of my reservoir, so i figured 2 four inch holes would let enough air pass through the cabinet and be moved up thru to my scrubber. if this does not make sense, please let me know.

jawnroot · Aug 2, 2008

You need to make sure light cannot get in through those holes. Even a little bit of light during flowering can herm your faves.

You can do what I'm doing and glue some type of high-flow carbon filter over your hole(s), or you can look into the [overpriced] deau passe intake filters.

CDM · Aug 2, 2008

Make a light trap, or use Black PVC for the passive intakes and keep the fans on.

Air flow is very important. I have been involved in this since the 70s and I think I know a little about what I am talking about. Having a small cab, without ventilation is not helping you any, its better to leave on your exhaust 24/7 then address your problems from there.

Restricting your passive intake with a filter is not going to help your grow any.. simply exausting your air will most likely solve your problem and give your plants much needed co2. Plants sitting in a small cab, with no ventalition simply do poorer.

I have never, ever seen a grow where ventilation was turned off at times that did well, unless the ventilation was off for the C02 generator to operate.

small cab, with odor problems is most likely solved with good ventalition and a carbon scrubber. nessasary equipment which you should have.

jawnroot · Aug 2, 2008

CDM said:
I have never, ever seen a grow where ventilation was turned off at times that did well, unless the ventilation was off for the C02 generator to operate.

Well CDM, I guess you've never seen my grows.

For the record, I never said I was going to run a small cab with no airflow. Indeed, my fan is a proper inline and rated at 150+ cfm (so, in other words, while the lights are on the air is being exchanged once every five seconds). Plants do not use CO2 in any significant amounts while the lights are off. Whatever is remaining in the cab is more than enough.

I have never left the ventilation fans on 24/7, never, and have always gotten A+ results. Granted, and as I said, you still need a fan inside the cab to move the air around while the main ventilation fans are turned off, and ideally some method of humidity control, but beyond that the ventilation fans do not need to be run 24/7. They are only on when the lights are on with my setup.

Now then, to the filter-upon-intake. Carbon filters for cars were designed to permit the greatest airflow possible, because the blowers on cars can only be so big. Having, lets say, a 10" x 10" filter on my intake will not significantly impact airflow efficiency, especially considering I'm using a 4" inline. Using a home-made light trap is almost guaranteed to restrict airflow more than a filter that was designed to pass air (isn't that a duh type of thing?).

If you've truly been into the indoor scene since the 70's, and have not seen a successful indoor grow where the main fan is turned off at lights out, then you haven't been making the rounds.

CDM · Aug 2, 2008

I thought you said you had a cab.. so ventilation is important.. You dont know me so Ill leave it at that. You think what you like.
but I say Ventilate its a good thing

jawnroot · Aug 2, 2008

I was the original poster CDM. And no, I don't know you, but get your facts straight before you start telling people they're wrong.

Pseudo · Aug 2, 2008

a light trap with a silkscreen mesh to keep bugs out

CDM · Aug 2, 2008

Ya I noticed, my facts are just fine thank you .... you asked for advise, if your so super grow man why ask? you know everything right??

LOL... You can do what you like.. I am not forcing anything on you..

there are lots of experianced people here, feel free to ask someone else? Lots of posers also.

Its such a simple issue.. why you having so many problems? its beyond me.
Anyway, Im not here to start a pissing contest with you.

Im perfectly happy with whatever you decide to do with your grow...

jawnroot · Aug 2, 2008

Take a hike CDM. I've always used butterfly valves on my intakes, and needed a different solution, thus I asked. Instead of giving some reasonable advice, you pop in and tell me I'm doomed to fail running the fans the way I do (even though I've been doing it that way for years with 100% success).

Been hitting the indoor scene since the 70's? Bullshit. People like you are what make this forum so irritating to use.

Microwido · Aug 2, 2008

Ok, here is what I use and I love it. Goto Home Depot and get a "Alergen reducing Air filter", its a furnace filter. There are 3 layers to the filter; 1 carbon black layer, 1 blue layer, and a green grate to hold it all together. Take it apart, and cut the Black carbon layer into 6 even pieces. Then duct tape atleast 3 pieces on top of each other over your intake, and now 0 light and smell gets through for 10$. Vwella.

:rasta:

A Filter For My Passive Intake?

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