question about a certain type of fan, DIY scrubbers.

what's up, i'm not a grower or anything but i am always interested in knowledge about cannabis, it's a core part of my life. anyways, with all these expensive fans specifically for grows, and the pc fans, then the inline duct fans for dryer vents, etc., does the type of fan make a considerable difference?

some fans are centrifugal and are blowers, etc. i was at wal-mart and they have mini 4inch high velocity fans for $7. why can't you just throw that little fan in a tube and attach a DIY scrubber?

the fan is incredibly fast for its size, way more powerful than any pc fan ive ever seen. i'm talkin about small areas, like 4 cubic feet. i've seen very few homemade scrubbers on here with pictures of their fans as well. and certainly a pc fan is not the proper fan.

so, does anyone have experience with these mini fans? they are on amazon as well for a little bit more money.

any pictures with homemade scrubbers and fans attached in micro boxes? i'm not interested in mini pc fan setups really, those don't interest me. also, does the coffee can scrubber work any different than the pencil cup scrubber? the coffee can is not mesh screen all the way thru like the pencil cup is, so i imagine airflow and carbon coverage is different.

even though no ones answering, i'll ask another. is the nylon covering the scrubber a fire hazard with CFL? is a CFL a fire hazard?

I've run those small 4" massey fans in 4" ducting before but they lack the static pressure to push through a filter...they make decent booster fans or emergency fans though.

I think the 'catch on fire temp' for nylon is much higher than the surface of a cfl could produce.

yea the massey fans are what i was talking about, now branded PMX at wally world for 7 bucks. I also threw some nylon on a regular incandescent bulb for about ten minutes and nothing happened, so clearly CFL will do no harm.

One more question.. I don't know much about electricity, but I am under the assumption that as long as I do not exceed 15 amps, I can connect as many power strips to each other as I want, right?

For instance, two strips in the box with light bulbs+socket adapters both plugged into another strip with fans all plugged in another strip to the wall. Is this bad? Six 26 watt lights plus four 0.35amp fans adds up to about nothing so am I in the clear?


edit: all the power strips state 15 amp maximum

Edited by johnneyb420, 21 May 2012 - 12:35 AM.

so does anyone know about daisy chaining power strips as long it's under 15 amps total? as soon as everything is safe, my friend's giving me $250 for this box and i'd really like to get that asap.

yeh I think it's fine...the whole danger issue with plugging lots of stuff into one socket is due to pulling too much energy rather then # of items.

You could always buy a 'kill-a-watt' and plug into it to see exactly how much wattage you're running though it. I bought one for that very purpose. They're about 25$ and they're really handy to have to check other stuff around the home. You can figure all this out with math and stuff...but they're a pretty cool tool to have anyways

*do not plug 1000w ballast into kill-a-watt...they tend to melt at around that wattage, still works though lol

** not an electrician!

Thanks man I appreciate the information. I'm trying to build my friend a box and he will pay me a good chunk of change for it if I can have it completely safe and noise proof so his wifey can't find it.

I was having trouble keeping temperatures down. It's 17 inches high, 16 inches across, and 23 inches deep, about the size of three small little pc setups. I have 6x26 watt CFLs, three 4in PMX high velocity fans for circulation, one PMX 4in fan connected to the pencil cup scrubber, and 2 120mm pc fans for intake, one 80cfm and one 40cfm. I'm thinking 88 is the best it can get in such a small spot? When it's really hot it can go up to 92.

Or the problem is airflow thru the scrubber and/or light traps? I really don't know.

Edit: the scrubber is connected to the exhaust, and the two intake fans are NOT stacked, they are side by side.

The room I am testing it in is also on the top floor, in the upper 70s. That could also be the problem. Perhaps when it is moved to his house it will be in a colder location.

Edited by johnneyb420, 22 May 2012 - 07:22 PM.

it hit 91 and it's like 77 in the room, maybe 75.


i have a feeling if i detach the pencil cups and drill holes in the bottom, it will be minimal difference so i haven't done that, not worth the trouble. i think the problem is the exhaust fan, it is one of the round ones hanging. what can i do to get air flowing nicely?

the exhaust barely has airflow, but there is some, it is very warm. the intakes work great.


edit: I left the temp. meter out in the room, and it says 79 so perhaps it is normal to be ten above or so in the box. still doesnt feel that warm, the ac would kick on and it hasn't.


now it says 77 in the room, which is what i thought. so temps are rising about 15 degrees on the inside.

Edited by johnneyb420, 22 May 2012 - 09:43 PM.

Bought a carbon scrubber and a large stanley fan and fixed them together with plenty of duct tape. Still working many months later. Investing in a nicer fan is on the to do list, and would probably be ideal for more airflow if you want to do it right. But it is definitely an option for those on a budget or who like to reuse things.


edit: I had to modify the inside of my fan to make it work. I believe I took it apart, and cut off this plastic wall on the inside. I also sealed off the other intake on it so the only air going through that fan is coming from the carbon filter.

-yea If you have one of those circular yellow shop fans, and it is trying to pull air in from both sides....you might need to modify the inside slightly to make it more efficient. There should be a plastic rib that separates the fan into two sides. I removed it, and sealed up all the seals with hot glue.

Edited by RongBip, 22 May 2012 - 09:34 PM.

the problem is this is going to be in my friends house where his wife absolutely cannot find out, so a large fan of any sort is out of the question. i tried an ultra kaze 130 cfm fan 3000 rpm and it sounded like a leaf blower. this has to be all around stealth, odor free, and low noise.

based on my available size in there, what can i do or buy and still have enough room for whatever he does with it.

i would consider buying a real 4in hydro fan, yet i hear those are just too loud and probably overkill for something this size.

Super stealth so his wife does not find out... HA! They always find out, its in their blood. Good luck with this because fans are either noisy or expensive.

yeah he knows there is some sort of risk. anyways, any ideas? does anyone know the math involved for airways and all that? or is 90-95 degrees acceptable? the box is really nice and completely light proof. i took two walls of emergency blanket down and the temp still was at 90.

i really would like to get this down to an acceptable temperature, someone here has got to have a solid answer with maybe some math involved or something, what can i do? my light traps are simply boxes placed on the outside behind the fans, about 3 inches deep, expelling at the bottom. so, the air shoots out of the fan and hits the cardboard wall and has to travel down a few inches. on the intake, the air is sucked in from the bottom and travels up basically an inch, which is so minimal that is why my intakes work great.

my problem is the exhaust and that goddamn pencil cup filter which no one has been able to show their fans connected to it with positive results. without the filter the box vents like a champ and will get down to room temperature basically, so my exhaust plus that stupid cup filter is the problem.

any ideas guys?

I am running a fan like you have with a simple coffee can carbon filter. The general rule for airflow is the air in your cab needs to exchange every 5 mins and the fan you have will do fine since my grow box is twice the size. Be sure to remember that your intake needs to be 2x bigger than your exhaust, since the actual diameter of the fan is 6 inches (the blade is 4 inch) you will need 2 six inch holes towards the bottom of your box with that you should see an improvement

when you put your hand behind your exhaust, do you feel lots of hot airflow or just some? perhaps the coffee can filter is much more efficient.

how precise does the 2x intake to exhaust have to be? because i have roughly twice the intake. it is very close, with two 120mm fans as intake and one 6in diameteter exhaust.

maybe i should make the coffee filter and see if airflow is any better? i can almost feel no airflow whatsoever, the filter severely restricts everything. is your filter as small as mine in the photo above?


also, what if i were to add a small 80mm intake above the other two intakes on the side? i didn't do any pi x r squared crap but i think that would help significantly, right? sucks every time i need to make an adjustment, this thing gets completely disassembled.

Edited by johnneyb420, 23 May 2012 - 03:55 PM.

ok im sure there is a reason for this, but when i turn off my intake fans on the side, the back exhaust fan works much easier and more hot air is released than when the intake fans are on. what the hell does that mean!? would it be better to have intakes that are just holes rather than fans? i have no idea what the cfm of those 4in fans from wall mart are.

Try running just the exhaust and use a lighter to see if the intake sucks more air with the fans off. You might be pushing more air in then the exhaust can remove. That's how I roll. Just and exhaust fan and the air gets sucked into my intake hole.

i thought it was running better with the intakes off, yet the temperature was 88 with them off and 86 with them on. this is driving me crazy haha, the room temperature is like 72 so it should be a lot cooler.

i dont know if i should add the 80mm intake or what, or just leave it how it is and accept 95 degrees on days that are hot as hell.

maybe i should try the coffee filter scrubber, because this fan cant pull shit thru the pencil cup.

With my filter I am pushing through the filter not pulling so that may be some of it too. but if you do try the coffee can filter put no more than a half an inch of Carbon in it and you should see a change. I also notice my fan has crappy sucking power (static pressure i think its called) but it pushes air like a mofo (and sorry about the late reply, forum was down all day today)

Try running just the exhaust and use a lighter to see if the intake sucks more air with the fans off. You might be pushing more air in then the exhaust can remove. That's how I roll. Just and exhaust fan and the air gets sucked into my intake hole.

From the many journals I have read the passive intake is the best thing to use

holy shit ive been trying to log in for a day now! when the site went down my password went with it for some reason, and i couldn't log back in until today, even with the temporary passwords sent to me.

the temperature is hotter without the exhausts on, so they are helping. i might just leave it as it is, it gets to 88-90, but the more i read, those are acceptable temperatures.

people have had positive results with high heat, i'm guessing it should do fine in 90 degrees, it is what it is.