Help with temp and odor control in 4x4 tent

Hey guys,

This is going to be a long post so I apologize in advance.

I have a 4x4 Gorilla tent with the vertical extension and I am running a single 600 Watt HPS Blockbuster 6 air cooled reflector. I have a 200 CFM fan blowing into the reflector and venting out of the tent.

For exhausting the tent, I have another 200 CFM fan pulling through a 200 CFM Phresh filter. Both fans are outside of the tent.

Odor control is spot on as I first tested by drying my modest 3 plant outdoor harvest in the tent. Once I got my grow started and closed up the tent, temps skyrocketed into the 90's. The tent is in my basement which is at a consistent 70 degrees. It appears that a 200 CFM exhaust fan is just not going to cut it, huh?

The room that the tent is in a 17'x13' section of my basement that I walled off. From the outside moving in, the materials are 5/8" drywall, studs, 2x4 Roxul insulation and then 1" XPS Dow Board. The room has a steel door to enter. I did the best job I could to make this room as air tight as possible. Inside of this room I have a 400 CFM fan pulling through a 400 CFM Phresh filter which vents out of the room into the other side of the basement. This was purely an extra level of odor control.

The original design used the two intakes to feed the light fan as well as the tent as a passive intake. I have since changed this so that both intakes are passive and the tent is getting it's air from the room.

Odor management is top priority!

So I have two different routes I've been considering. Replace my tent exhaust with a much more powerful fan and larger carbon filter. If I go this route, how many CFM do I need?

The 2nd option is to just get rid of the tent altogether. This is appealing because it will make watering and day to day tending considerably easier. As I mentioned, the room we are in is roughly 17'x13' by 9' tall so we're looking at roughly 2000 CFM. If I am able to keep this room negatively pressurized, is it reasonable to assume that no odor will escape? Going this route would surely mean I need to be exhausting much more than 400 CFM but I have no idea how much more.

Any thoughts would be greatly appreciated. I'm almost 2 weeks into a 12/12 experiment so I have a little time still before we start stinking.

http://www.amazon.com/VenTech-IF6CF620-Inline-Virgin-Charcoal/dp/B0052ZPMAG


order control and temp controll on full power u are replacing the air in the tent every 15 secs ..........as long as the tent is on a passive intake with air temps around 70 68 your plants will be fine and the smell will be controlled as long as the door is shut ..........door open it going to stink


to cover the times u have the door open or anything else get one of these
http://www.ebay.com/itm/NEW-LIVING-ALPINE-AIR-PURIFIER-OZONE-GENERATOR-UV-ALLERGY-ASTHMA-RELIEF-/161042404879?pt=LH_DefaultDomain_0&hash=item257ee0160f

this will clean the air great no smell or anything ...........just do not add this to your ozone is not the best for plants........use it when u need it u can ctrol the fan speed the amount of ozone ..........the other cleaning effects are just bonus

justugh said:

http://www.amazon.com/VenTech-IF6CF620-Inline-Virgin-Charcoal/dp/B0052ZPMAG


order control and temp controll on full power u are replacing the air in the tent every 15 secs ..........as long as the tent is on a passive intake with air temps around 70 68 your plants will be fine and the smell will be controlled as long as the door is shut ..........door open it going to stink


to cover the times u have the door open or anything else get one of these
http://www.ebay.com/itm/NEW-LIVING-ALPINE-AIR-PURIFIER-OZONE-GENERATOR-UV-ALLERGY-ASTHMA-RELIEF-/161042404879?pt=LH_DefaultDomain_0&hash=item257ee0160f

this will clean the air great no smell or anything ...........just do not add this to your ozone is not the best for plants........use it when u need it u can ctrol the fan speed the amount of ozone ..........the other cleaning effects are just bonus

Click to expand...

So you think increasing from 200 to 440 CFM will do it?
Regarding the OZONE, I've read quite a bit and I'm a little worried about the health risks. I do have a ONA kit I bought that I thought I could use as you suggested. Thank you for taking the time to respond.

Hot Diggity Sog said:

So you think increasing from 200 to 440 CFM will do it?
Regarding the OZONE, I've read quite a bit and I'm a little worried about the health risks. I do have a ONA kit I bought that I thought I could use as you suggested. Thank you for taking the time to respond.

Click to expand...

well the carbon scrubber will take care of the smell going out ...the 440 cfms will cause negitive pressure so the tent will not be leaking smell untill the door is open

even if u add a powered intake as long as u keep the cfm under 440 u should always have that negitive pressure


as for the ozone gen yes the com units are deadly but that is do to the amount they kick out ............the one i linked to u is 100% safe i have it running in this room as i type .....i am about to clip a plant down for drying so prepping the air

plus it is going to help u ,,,,,,,,,it cleans the air virus and mold ..........has a neg ion /hempa/ozone /UV

i would not tell yah anything bad man ........i need all the good karma i can get for later so hence why i spend my time here doing this

but i have run 2 600w in the same tent at the same time using a 440 and cooltube system if i could keep the temp at 68 in the area the exhaust temp was running 78 before passing over the first hid light

I did not mean to imply that I did not believe you. The fact that you have personal experience with it makes me feel better and I will consider picking it up. I'm just hyper sensitive to poisons and what not is all.

Let me ask you this:

When I closed up my tent and had the 200 CFM pulling through the carbon filter, I rigged up a flimsy piece of plastic on the intake ducting to try and visually see the air flow coming into the tent passively. The dang thing did not move at all...nothing. As if no air was coming in at all. At the time, the ducting from my basement outer room into my tent had about a 10 foot run. No major bends or anything. Does this make sense? I fully expected that I would see at least some movement...some visual indication that air was being drawn in.

I had the obvious negative pressure as the walls of tent were sucked in.

I realize that tents are not actually air-tight nor are they meant to be but it sure seems logical that air will enter thru the path of least resistance which should be a gaping 6" piece of ducting. I made sure to tie off all of the other duct openings in the tent.

Hot Diggity Sog said:

Let me ask you this:

When I closed up my tent and had the 200 CFM pulling through the carbon filter, I rigged up a flimsy piece of plastic on the intake ducting to try and visually see the air flow coming into the tent passively. The dang thing did not move at all...nothing. As if no air was coming in at all. At the time, the ducting from my basement outer room into my tent had about a 10 foot run. No major bends or anything. Does this make sense? I fully expected that I would see at least some movement...some visual indication that air was being drawn in.

I had the obvious negative pressure as the walls of tent were sucked in.

I realize that tents are not actually air-tight nor are they meant to be but it sure seems logical that air will enter thru the path of least resistance which should be a gaping 6" piece of ducting. I made sure to tie off all of the other duct openings in the tent.

Click to expand...

ok the 200 cfm was cut down to maybe 160 ..........the distance u had it running was allowing it to slow down .........rem the ducting is not flat/smooth inside those ridges act as wind breaks .........it is why u see is all streched or all tight together to lessen that effect ,,,,,,,u just had enough distance to cause it to feel like nothing

that fan /filter combo i linked yah will get u 400 cfms ..............just strech out the ducting .......if u are a hid look at insulted ducting this will keep the air from warming up outside the tent so much ...............i have something like that going about 15 feet with 2 90 degree bends and the ejection air is enough to be felt tho a 2 foot bush in front of the window .....insulted ducting


as for your intake here build your self this ...............intake filter box .............it cleans the air before it gets into the tent cutting down on chances of mold

justugh said:

ok the 200 cfm was cut down to maybe 160 ..........the distance u had it running was allowing it to slow down .........rem the ducting is not flat/smooth inside those ridges act as wind breaks .........it is why u see is all streched or all tight together to lessen that effect ,,,,,,,u just had enough distance to cause it to feel like nothing

that fan /filter combo i linked yah will get u 400 cfms ..............just strech out the ducting .......if u are a hid look at insulted ducting this will keep the air from warming up outside the tent so much ...............i have something like that going about 15 feet with 2 90 degree bends and the ejection air is enough to be felt tho a 2 foot bush in front of the window .....insulted ducting


as for your intake here build your self this ...............intake filter box .............it cleans the air before it gets into the tent cutting down on chances of mold

Click to expand...

Okay, thanks man! The first thing I notice with my setup is that my ducting is not stretched tight...it's pretty saggy.

Your looking at too many options/fixes at once.

First and foremost to make an assessment we need to know the high temps in the tent, outside the tent, and in the rest of the basement.



- Jiji

justugh said:

http://www.amazon.com/VenTech-IF6CF620-Inline-Virgin-Charcoal/dp/B0052ZPMAG


order control and temp controll on full power u are replacing the air in the tent every 15 secs ..........as long as the tent is on a passive intake with air temps around 70 68 your plants will be fine and the smell will be controlled as long as the door is shut ..........door open it going to stink.

Click to expand...

Just my experience, but I have one of these, and the carbon filter does not work well. I had to send the first set back because the fan bearings started to go, and the filter did not control the smell at all. I even have a speed controller on the fan and tried slowing it down so the filter could scrub better, but no luck. The fan works fine this time though. I'm going to get a phresh or can filter because odor control is a priority for me as well. I have that fan in my 4x8 tent and it works very well, creates plenty of negative pressure.

blackforest said:

Just my experience, but I have one of these, and the carbon filter does not work well. I had to send the first set back because the fan bearings started to go, and the filter did not control the smell at all. I even have a speed controller on the fan and tried slowing it down so the filter could scrub better, but no luck. The fan works fine this time though. I'm going to get a phresh or can filter because odor control is a priority for me as well. I have that fan in my 4x8 tent and it works very well, creates plenty of negative pressure.

Click to expand...

well if u are in the USA and have the cash grab yourself this
http://www.ebay.com/usr/foothill-carbon-filters?_trksid=p2047675.l2559

they sell refillable ones so once the carbon is no good u can dump out and just replace that saving yourself a good amount of money once u invest .......i own a 4 and 6 inch had them for 2 years now redid the carbon one time ......works great one is on my flowering tent other is on drying tent can not smell shit

jijiandfarmgang said:

Your looking at too many options/fixes at once.

First and foremost to make an assessment we need to know the high temps in the tent, outside the tent, and in the rest of the basement.



- Jiji

Click to expand...

Temps in the main basement:
68/73 F. This is a 3 month sample size

Temps in tent with door open
68/84

Temps in the sectioned off room
68/75

I have not run the tent closed except for my initial test in which the temps rose to 92 within a short period of time.

blackforest said:

Just my experience, but I have one of these, and the carbon filter does not work well. I had to send the first set back because the fan bearings started to go, and the filter did not control the smell at all. I even have a speed controller on the fan and tried slowing it down so the filter could scrub better, but no luck. The fan works fine this time though. I'm going to get a phresh or can filter because odor control is a priority for me as well. I have that fan in my 4x8 tent and it works very well, creates plenty of negative pressure.

Click to expand...

Not that I have any experience with anything else, but I will be sticking with Phresh filters.

You can get rid of the tent if you want, thats up to you.

For fans, I'm not familiar on what those are. If they are regular axial fans, they work horrible under pressure. Drawing air through a carbon filter really drops the cfm.

If your only going to run one 600 light, I would get a centrifugal 6" fan above 400 cfm (I'm partial to vortex vtx, but any should do). Match a carbon filter (I always like to oversize) and hang the filter from the ceiling of the tent. Then run it to the light, then your fan, then outside to main basement. Passive intake on tent.

It looks like the passive intakes on your room wall are big enough...

I would ditch the fans, or if you want you could use a small fan and a carbon filter directly mounted for additional air scrubbing.

I wouldn't worry too much on air change outs. Basically, its such a large area and a small tent, and one light.

- Jiji

jijiandfarmgang said:

You can get rid of the tent if you want, thats up to you.

For fans, I'm not familiar on what those are. If they are regular axial fans, they work horrible under pressure. Drawing air through a carbon filter really drops the cfm.

If your only going to run one 600 light, I would get a centrifugal 6" fan above 400 cfm (I'm partial to vortex vtx, but any should do). Match a carbon filter (I always like to oversize) and hang the filter from the ceiling of the tent. Then run it to the light, then your fan, then outside to main basement. Passive intake on tent.

It looks like the passive intakes on your room wall are big enough...

I would ditch the fans, or if you want you could use a small fan and a carbon filter directly mounted for additional air scrubbing.

I wouldn't worry too much on air change outs. Basically, its such a large area and a small tent, and one light.

- Jiji

Click to expand...

The fans I'm using are these:
http://www.hvacquick.com/products.php/residential/AirFlow-Boosting/Inline-Air-Booster-Fans/S-P-TD-SILENT-Series-Inline-Fans
I found these from another grower's journal and he was ranting about how good they were. Since fan noise is a consideration I went with them.

Alright...so the consensus seems to be if I double my exhaust pressure that I should be fine. Since I'm already equipped to vent my light separately, is there a reason to include the light in this single vent design? Just simplicity?

If I did decide to drop the tent, do you think if I added an additional 500 CFM exhaust giving me (2) 500's that I would enough negative pressure to keep smells confined to the room?

Those are axial hybrid aka mixed axial.

The centrifugal is going to be noisier for sure, not sure how much that matters. (I'd still do it this way and figure out a way to silence it)

You could get a axial hybrid fan 6 inch.

Keep it Simple. Negative pressure is negative pressure. Don't need massive amounts of vacuum. Just want all air to be filtered instead of escaping.

You want air transfer, equalization of your basement temps.


- Jiji

Edit....come to think about it, with a 6 inch centrifugal fan in that tent might suck the walls in pretty tight if you shut the door. Depends on how well the the vents are.

jijiandfarmgang said:

If your only going to run one 600 light, I would get a centrifugal 6" fan above 400 cfm (I'm partial to vortex vtx, but any should do). Match a carbon filter (I always like to oversize) and hang the filter from the ceiling of the tent. Then run it to the light, then your fan, then outside to main basement. Passive intake on tent.
- Jiji

Click to expand...

I have a question. When using a cooltube, is it better to push or pull the exhaust through the tube? Some say pulling heated air through the fan will shorten its life. What do you say?

Pulling air is more efficient, unless your using really sharp (180 degree) bends in flexible tube.

Heat on a centrifugal fan degrading lifespan.....Not really. I mean I'm sure its not better, but it really doesn't matter. My centrifugal fans are warrantied for 5-10 years, and I've only had 1 fail and that was a stupid C.A.P. fan (and it just moved air, not hot air).

- Jiji

Real 200cfm fans? Or booster fans that can reach up to 200cfm in an enclosed system w/ a blower?

Get a 6" 440cfm fan for exhaust/filter.

Filter>light>fan>exhaust.....