Air movement question, I need some input please!

Rickcin · Jun 21, 2021

I’m a first timer, growing two plants in a 2x4x6 foot height tent with an LED 1500 watt light.

For proper air circulation, do I need to run both the carbon filter exhaust air ( sitting outside of the tent) and a 6 inch fan in the tent

I know nothing about growing this stuff but would guess that either the fan or the carbon fan would provide ample air circulation!

please let me know what I should be doing, thanks️

jguit · Jun 21, 2021

A single fan should do. In my main tent, I have the carbon filter inside my tent with an inline fan pulling air through the filter. The openings/vents in the bottom of the tent are opened for fresh air.

Aqua Man · Jun 21, 2021

You need air movement in the grow space. Alot will depend on the size of tent and plants.

An exhaust fan is just that...used to exchange air, exhausting hot air and bringing on fresh co2 rich air.

A circulation fan is used to mix new air equally in the tent so all the plants have good exposure to the fresh air.

So in short it depends on how you have the exhaust and intake flaps setup how well the air mixes. Plants exchange co2 and release moisture on the underside of the leaves so its important to have air movement under and through the canopy. It does not need to be direct airflow.... just air movement.

Ideally for your setup I would try to create a cyclone type effect with the circulation fan at the bottom of the tent. Facing the fan alone the wall to create good air mixing at the bottom. The exhaust fan will pull the air up and out and it will create a well mixed tent.

Think of it like an upside down toilet bowl.

To boot you want the exhaust fan pulling air through the filter and use a pre-filter. This will extend the life and increase the effectiveness of the filter.

Keep humidity below 70 as carbon filters don't do well in humidity areas

MI420Farmer · Jun 21, 2021

Aqua Man said:
You need air movement in the grow space. Alot will depend on the size of tent and plants.

An exhaust fan is just that...used to exchange air, exhausting hot air and bringing on fresh co2 rich air.

A circulation fan is used to mix new air equally in the tent so all the plants have good exposure to the fresh air.

So in short it depends on how you have the exhaust and intake flaps setup how well the air mixes. Plants exchange co2 and release moisture on the underside of the leaves so its important to have air movement under and through the canopy. It does not need to be direct airflow.... just air movement.

Ideally for your setup I would try to create a cyclone type effect with the circulation fan at the bottom of the tent. Facing the fan alone the wall to create good air mixing at the bottom. The exhaust fan will pull the air up and out and it will create a well mixed tent.

Think of it like an upside down toilet bowl.

To boot you want the exhaust fan pulling air through the filter and use a pre-filter. This will extend the life and increase the effectiveness of the filter.

Keep humidity below 70 as carbon filters don't do well in humidity areas

Agree with AquaMan 100%. Must have an exhaust fan going no matter what. I've tried using only a circulation fan and moisture built up over a 24hr period on the walls. You can run just an exhaust fan and be fine but as plants grow, yes you need a cyclone like effect, pushing air around. For mature veg and immature flowering, I have the circulation fan on the floor to move air through the bottoms. At late flowering, I hang the circulation fan to hit the buds lighting and reduce the risk for rot and other issues.

weed_weasel · Jun 21, 2021

Rickcin said:
I’m a first timer, growing two plants in a 2x4x6 foot height tent with an LED 1500 watt light.

For proper air circulation, do I need to run both the carbon filter exhaust air ( sitting outside of the tent) and a 6 inch fan in the tent

I know nothing about growing this stuff but would guess that either the fan or the carbon fan would provide ample air circulation!

please let me know what I should be doing, thanks️

Are you concerned about the smell? If not I wouldn't bother with a carbon filter.

Rickcin · Jun 21, 2021

If I’m understanding this correctly; best case is open bottom flaps, place fan on the bottom of the tent while my 4 inch ducted carbon filter will be sucking out air from the top of the tent. Correct

Rickcin · Jun 21, 2021

weed_weasel said:
Are you concerned about the smell? If not I wouldn't bother with a carbon filter.

No concern for the smell, the tent is in a very large basement.

Aqua Man · Jun 21, 2021

Rickcin said:
If I’m understanding this correctly; best case is open bottom flaps, place fan on the bottom of the tent while my 4 inch ducted carbon filter will be sucking out air from the top of the tent. Correct

Correct

lvstealth · Jun 21, 2021

Well... I have a bunch of fans. My exhaust fan runs almost always at some speed.

I use fans to move air, but also to alliviate pockets of moisture or fix hot spots. They are on smart plugs, some run minutes, some hours, but if you saw it you'd think it was a random thing of fans on and off!

But it works. And I like the smart controls and using ifttt and alexa and Google home.

To be more specific in answering you, run the exhaust when humidity is high or temps over 75f. Which is almost always. When temp falls humidity rises, those numbers are a good start to dialing things in.

Next, CFM. You want your air changed often. Lots of factors here, but I find more is better than less.

That takes care of air out. So, air in is next. You want as much coming in as going out. To do this, you can use fans, or open vents or flaps... But that is a must. I like math and numbers, but basically, zip it up, turn out and in fans on. If tent sucks in - you need more. If it puffs out, less.

The "air in" is most of the problem. If it's hot, cold, dry, humid, it matters. I have found the dehumidifier the most valuable piece of equipment I have for environment. Drier air works better. Even if you want to have 65% rh, start the air coming in at 43%.

My room the tents are in is kept at 73f, with 43% rh. I bring this into my tents with an intake fan (a fan blowing into tent) that is 1/2 the cpm of the exhaust. The other 1/2 is in how I'm running both tents on one fan and some math.

Anyway, more or less, you'll most always have some fan running. And more than not, more than 1

Rickcin · Jun 21, 2021

weed_weasel said:
Are you concerned about the smell? If not I wouldn't bother with a carbon filter.

jguit · Jun 21, 2021

Rickcin said:
No concern for the smell, the tent is in a very large basement.

My flowering tent is in a large basement as well and without the carbon filter running both 1st and 2nd floors will reek of weed in no time!

Rickcin · Jun 21, 2021

lvstealth said:
Well... I have a bunch of fans. My exhaust fan runs almost always at some speed.

I use fans to move air, but also to alliviate pockets of moisture or fix hot spots. They are on smart plugs, some run minutes, some hours, but if you saw it you'd think it was a random thing of fans on and off!

But it works. And I like the smart controls and using ifttt and alexa and Google home.

To be more specific in answering you, run the exhaust when humidity is high or temps over 75f. Which is almost always. When temp falls humidity rises, those numbers are a good start to dialing things in.

Next, CFM. You want your air changed often. Lots of factors here, but I find more is better than less.

That takes care of air out. So, air in is next. You want as much coming in as going out. To do this, you can use fans, or open vents or flaps... But that is a must. I like math and numbers, but basically, zip it up, turn out and in fans on. If tent sucks in - you need more. If it puffs out, less.

The "air in" is most of the problem. If it's hot, cold, dry, humid, it matters. I have found the dehumidifier the most valuable piece of equipment I have for environment. Drier air works better. Even if you want to have 65% rh, start the air coming in at 43%.

My room the tents are in is kept at 73f, with 43% rh. I bring this into my tents with an intake fan (a fan blowing into tent) that is 1/2 the cpm of the exhaust. The other 1/2 is in how I'm running both tents on one fan and some math.

Anyway, more or less, you'll most always have some fan running. And more than not, more than 1

I understand, balanced air flow in and out is desired as opposed to negative or a positive air pressure. I’m in a 1800 sf basement so the temperature is pretty consistent at 65 degrees while humidity is the variable that I can adjust (lower only) with a decent sized humidifier. Perhaps I will need a little heat once winter arrives since I believe I need to maintain 70 degrees.

Rickcin · Jun 21, 2021

jguit said:
My flowering tent is in a large basement as well and without the carbon filter running both 1st and 2nd floors will reek of weed in no time!

so I guess the same will happen here once my plants get big! Currently, they are just starting their 3 week from being planted as seeds.

jguit · Jun 21, 2021

Rickcin said:
so I guess the same will happen here once my plants get big! Currently, they are just starting their 3 week from being planted as seeds.

Certainly. The smell in veg isn't all that bad but once they start flowering, look out! ha..

lvstealth · Jun 21, 2021

Yes. Bring the humidity in the basement down to 40-45%. When you pump it into the tent your humidifier will work like it's suppose to. And any cooling/heating works fast and all over.

Bbonez · Jun 21, 2021

Rickcin said:
I’m a first timer, growing two plants in a 2x4x6 foot height tent with an LED 1500 watt light.

1500W in a 2X4?

Rickcin · Jun 21, 2021

jguit said:
Certainly. The smell in veg isn't all that bad but once they start flowering, look out! ha..

I can only hope

Rickcin · Jun 21, 2021

Bbonez said:
1500W in a 2X4?

Yes!

Rickcin · Jun 21, 2021

lvstealth said:
Yes. Bring the humidity in the basement down to 40-45%. When you pump it into the tent your humidifier will work like it's suppose to. And any cooling/heating works fast and all over.

Yes, but now I’m just beginning with my 3 rd week of growth and the tent humidity is only 57% so I’m guessing that perfect and should not be much lower

lvstealth · Jun 21, 2021

Oh! And one more piece of knowledge...

The basement is huge. More space to control. If you build out a room to put your tent in, you will save loads of money, lots of time, and you won't want to chew nails trying to get temp AND humidity for day AND night set up.

Just a small room, 10x10 more or less. Use a corner, that gives you two walls. You can google framing a room. I'm an old disabled granny and I can do it. Then use the boards at the box store that insulate instead of sheetrock. Might take a weekend.

Much easier to control a smaller space than a whole basement

If you don't, this will be an ongoing problem

Air movement question, I need some input please!

Air movement question, I need some input please!

Rickcin

jguit

Aqua Man

MI420Farmer

weed_weasel

Rickcin

Rickcin

Aqua Man

lvstealth

Rickcin

jguit

Rickcin

Rickcin

jguit

lvstealth

Bbonez

Rickcin

Rickcin

Rickcin

lvstealth

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