Exhaust in right position?

[Terepeneterrapin]

Hi there 420mag,

Long time lurker, first time poster. Decided to setup a grow using passive air intake nudged on by the power of the exhaust.

Only problem is, I worry I placed my exhaust fan in the wrong place. Currently my exhaust is positione above the intake air hole side of my tent, instead of the opposite side. Is this a problem, as I worry the air that comes in is effective being sucked out immediately.

Any thoughts or experience on this ropic Would be greatly appreciated.

 

[013]

Hi Terrapin,

Welcome to 420!

Ok most of us run multiple fans, the exhaust is great but keep one pointed at soil line and another with gentle breeze on your foliage - more air will help the plants transpire quicker which means they shed water better and therefore the uptake of water from soil is faster. These fans will help passive air intake too, in fact open all lower intake vents.

But yes you are correct - It does help air to cross the tent instead of going straight up and out. Draw fresh air into the tent from down low and exhaust warm air out up top... this helps the natural cycle of cool air sinks and warm air rises. Obviously you don’t need 2 fans on a tiny plant but a bigger plant will benefit, less risk of critters, bud rot and pm

more people will stop in soon

 

[Rexer]

Far from being a deal breaker. Set it up, keep an eye on temps and it's usually recommended to have an oscillating fan inside blowing across the foilage (as 013 said).
As long as there is air movement inside you should be ok. In fact...see if you can put the oscillating fan on same side as your intake & exhaust pushing air to the other side of the tent.

You want to avoid pockets of stagnant air.

 

[Terepeneterrapin]

Thanks 013 and rexer. I’ll keep those things in check. My grow is still literally at germination as I’ve just started. To be safe I’ll move my exhaust to the other side and try open a few more air holes to allow the passive intake.

Normally with the oscillating fans I’ve heard too much wind can’t be good as well right? In your exp, do those small clip on fans do the trick.

 

[Bush Doctor 77]

You want ventilation and circulation. The farther apart intake is from exhaust, the better the circulation. Most of us use a fan to blow directly across the plants for the best circulation.

 

[Terepeneterrapin]

Also rexer would tempt be the indicator that the exhaust is just vacuuming the intake air before it even spreads?

 

[Bush Doctor 77]

Thanks 013 and rexer. I’ll keep those things in check. My grow is still literally at germination as I’ve just started. To be safe I’ll move my exhaust to the other side and try open a few more air holes to allow the passive intake.

Normally with the oscillating fans I’ve heard too much wind can’t be good as well right? In your exp, do those small clip on fans do the trick.

Plants grow best outside, in the wind. It aids in plant breathing, and builds strong branch structure. I have an 18 inch fan blowing down on my 4X4 SCROG. If you have a strong exhaust, passive intake is plenty w/a circulation fan.

 

[Terepeneterrapin]

Plants grow best outside, in the wind. It aids in plant breathing, and builds strong branch structure. I have an 18 inch fan blowing down on my 4X4 SCROG. If you have a strong exhaust, passive intake is plenty w/a circulation fan.

Wow 18 inch fan. Well budget wise I’m trying to see if a few gentle fans can help with the circulation. My exhaust iirc is approx 125+ CFM. I might’ve got that wrong but I remember that I checked out for covering more than the tent needs

Growing in a 3x3.

 

[Rexer]

I'm a bit unconventional. My active intake is a 6 inch fan, and exhaust is an 8 inch. Both reduced to 4" (oversized for extra torque as they have to push/pull air through ducts for some distance ). I also have a 4 inch fan inside on 24/7 taking the hottest air at the top and bringing it down. I have one small clip fan blowing the top of the foilage which is almost touching my HPS. Then I have a tower fan on its side blowing the bottom of the plants and through the foilage.
It's overkill, but I have even temps, zero hot spots, and constant air movement mitigating chance of mildew/bud rot.

My point? You can have them on the same side, and plants can still be fine.

Temp can be an indicator for sure, multiple temp sensors can help figure out hot spots. Don't be shy on airflow, your plants will thank you.

Edit - I should add I grow in an insulated grow cabinet

 

[Rexer]

Also rexer would tempt be the indicator that the exhaust is just vacuuming the intake air before it even spreads?

For checking....leave it on for an hour. Let the airflow do it's thing, then make small adjustments as necessary. Also, remember the plants will get much bigger and obstruct airflow somewhat (depending on layout), dunno...i need more coffee

 

[Terepeneterrapin]

I'm a bit unconventional. My active intake is a 6 inch fan, and exhaust is an 8 inch. Both reduced to 4" (oversized for extra torque as they have to push/pull air through ducts for some distance ). I also have a 4 inch fan inside on 24/7 taking the hottest air at the top and bringing it down. I have one small clip fan blowing the top of the foilage which is almost touching my HPS. Then I have a tower fan on its side blowing the bottom of the plants and through the foilage.
It's overkill, but I have even temps, zero hot spots, and constant air movement mitigating chance of mildew/bud rot.

My point? You can have them on the same side, and plants can still be fine.

Temp can be an indicator for sure, multiple temp sensors can help figure out hot spots. Don't be shy on airflow, your plants will thank you.

Edit - I should add I grow in an insulated grow cabinet

Wow that definetly sounds..intricate to say the least haha! Amazing system you got there.

Also guessing by what you’re saying you have your other fans on a time schedule? I assumed fans to be on 24/7. Or am I gravely misinformed. If I am wrong, im guessing it’s off at ‘night’ to stop oxygen intake?

 

[Rexer]

Wow that definetly sounds..intricate to say the least haha! Amazing system you got there.

Also guessing by what you’re saying you have your other fans on a time schedule? I assumed fans to be on 24/7. Or am I gravely misinformed. If I am wrong, im guessing it’s off at ‘night’ to stop oxygen intake?

My intake/exhaust fans are hooked up to a temp controller, they kick on as needed. All other ones, yes 24/7.
Fresh air is a good thing.
My setup - I only mentioned it so you're aware, more air movement isn't something to be afraid of.

013 & Bushdoctor gave great advice that's perfectly suited for what your after.

Take a good walkthrough some grow journals and look at how people have set them up. And feel free to ask any questions that arise!

 

[013]

Your rh will probably spike at night / lights off without some fan forced air circulation, don’t have to be the extraction fan running 24 X 7 but yeah I keep one or 2 smaller fans going around the clock depending on plant count and density of canopy etc

 

[Rexer]

Your rh will probably spike at night / lights off without some fan forced air circulation, don’t have to be the extraction fan running 24 X 7 but yeah I keep one or 2 smaller fans going around the clock depending on plant count and density of canopy etc

Thats a great point- RH will probably rise/spike (I DO need more coffee )

You keep a dehumidifier in your tent I imagine @013?

 

[013]

Same here Rexer - but an ice cold soda works for me! I have one but don’t run it since it spikes my temps, but it’s outside of tent in case I need it

 

[Rexer]

Same here Rexer - but an ice cold soda works for me! I have one but don’t run it since it spikes my temps, but it’s outside of tent in case I need it

Yeah I have one in there on a controller, but at this time of year it's not even kicking on. Loving growing in the colder weather!

 

[013]

Me too but I will love it even more if I can get these new beans to crank up!

Are you running an inkbird?

 

[Rexer]

Me too but I will love it even more if I can get these new beans to crank up!

Are you running an inkbird?

Yup, Wi-Fi Inkbird for temps (turns on intake and exhaust when too hot). One for humidity control and a third hooked up to keep my res from getting too cold.