Question: Grow box intake fan and fabric pots

So, I just built a new grow box that measures 150cm tall, 40cm deep and 75cm wide.
I am using a homemade LED light that is made out of regular LED bulbs with their globes removed and sure enough I ran into some overheating issues.
The temperature goes as high as 45 degrees centigrade (113 degrees Fahrenheit). That's really fucking hot.

For the first time in my life I am using a carbon scrubber/filter and I think that this filter greatly reduces the airflow of the exhaust fan.
So now, I am starting to realize that I can't get away with just a passive intake hole on the bottom of the box.
I do need an intake fan.

My question is: since I will be growing in fabric pots, how safe it would be to have an intake fan?
Obviously, that intake fan will be sitting close to the very bottom of the box and it's air stream will be hitting directly the side of one of the fabric pots. Will this make that pot dry out quickly and cause the plant problems?
Would it be OK to place the intake fan a little higher - just above pot level???
Is there any other workaround?

Thanks!

Guerilla Kush said:

this filter greatly reduces the airflow of the exhaust fan

Click to expand...

Yes it does. You need a better exhaust fan.

Guerilla Kush said:

I am using a carbon scrubber/filter and I think that this filter greatly reduces the airflow of the exhaust fan.

Click to expand...

Indeed. Some fans don't cope with static pressure losses as well as others. Centrifugal fans are the best at fighting restriction. Axial are the worst by far and mixed flow fans fall in the middle.

It's generally best to oversize the fan a little and use a variac to slow it down. This will help with the noise and will allow you to turn the fan speed up should the need arise.

Vortex VTX series inline fans are all I will buy.

Also, an intake fan won't really help the exhaust fan, instead it would likely create a positive pressure situation thus reducing the carbon filters effectiveness.

So don't waste any money on an intake fan, just get a better exhaust fan.

Renfro said:

Vortex VTX series inline fans are all I will buy.

Click to expand...

I took your advice and I will never look back. Running my 8'' VTX fan at 1/3 power and its still moving to much air- there are days the tent doesnt get over 70 degrees. And Ive got carbon filter, filters on the intakes of the tent, and the fan is moving air from upstairs downstairs in a constant circulation.

Thanks for the replies, guys.
I will take your advice and will try to invest in a better exhaust fan. My budget is very limited, though.
Also, noise is a concern in my case, because the grow box is in my bedroom, just 3 feet away from my bed.
How noisy are those Vortex VTX fans? Anything above 30 decibels would be a problem.


By the way, I found this at a good price. Would something like this be suitable? How different is this from a regular bathroom fan???
It looks like an ordinary fan to me, just put in a a fancy casing.

Guerilla Kush said:

Thanks for the replies, guys.
I will take your advice and will try to invest in a better exhaust fan. My budget is very limited, though.
Also, noise is a concern in my case, because the grow box is in my bedroom, just 3 feet away from my bed.
How noisy are those Vortex VTX fans? Anything above 30 decibels would be a problem.


By the way, I found this at a good price. Would something like this be suitable? How different is this from a regular bathroom fan???
It looks like a ordinary fan o me, just put in a a fancy casing.

View attachment 4785087

Click to expand...

That just looks like a shitty inline duct fan.

If its next to your bed and price is an issue, that is a problem. A 6 or 8'' vortex vtx plus a VARIAC is going to run you about 250$. But an 8'' fan running at 10-15% will be silent and move a fuckload of air through a filter and whatever other restrictions are on it.

JoeBlow5823 said:

I took your advice and I will never look back. Running my 8'' VTX fan at 1/3 power and its still moving to much air- there are days the tent doesnt get over 70 degrees. And Ive got carbon filter, filters on the intakes of the tent, and the fan is moving air from upstairs downstairs in a constant circulation.

Click to expand...

Yeah when I put my 10 incher on my 2x4 tent and run it at like 35 - 40 volts off the variac you can't even hear it running and I get plenty of negative pressure and temps are equalized with the ambient. Can't beat it. I should have bought more of them when I found that sale, the 10 inchers were less than the 4 inchers! When I mounted the fan I used rubber isolators and it's screwed to the joists above. Hanging one with those ratcheting light hangers will also work to isolate any noise.

Renfro said:

When I mounted the fan I used rubber isolators and it's screwed to the joists above. Hanging one with those ratcheting light hangers will also work to isolate any noise.

Click to expand...

They are so well made and balanced noise isolation isnt even really an issue. Maybe if you were running 75-100%. maybe.

re: your questions about the fabric pots, I'd have to expect them to dry out faster unless you do something intentional to redirect how the incoming air routes to the point where the extraction fan/filter would pull it. You could perhaps do something to bring it up right below the canopy but above the pots and perhaps even use some type of barrier to further enforce that path of flow.

I'm using a small 2x4 for a side/experimental run in a tent right now with cloth pots. Mine sit in Rubbermaid bussing tubs and I put some heavy vinyl (i.e. shelving liner) on top of the pots for a light/evaporation barrier. The top coverings were there mainly to help build up the fungal layer on top when I top dressed and they help prevent drying out due to that. The tubs somewhat shield the lower portions of the pots. This way I still get air around the pots but 1 sits right beside the intake so I was already thinking of (worrying about) these same considerations.

I'm running an AC Infinity fan with their newer controller that allows you set a minimum intake speed (finally) and it then governs based on both temp and humidity. For me I see it's constantly running due to humidity trigger, not heat.

Though a mixed flow fan, I'm very satisfied so far with the AC Infinity fans and like Renfro is mentioning, oversize and run lower is key. They are DC fans and EC controlled so you don't need a variac for these. Beforehand I was looking into oversized + variac for sure.

My biggest fan challenges these days is more from the outlet whoooshing noise; In my 2 setups one exhausts into a bedroom and the other to the main upstairs loft area so fighting the noise is key for stealth in my case.

NewGrower2011 said:

I'm running an AC Infinity fan with their newer controller that allows you set a minimum intake speed (finally)

Click to expand...

What controller does this? This was my biggest complaint with them.

So 1st off, do not buy they one with the better controller. Get the base model - they don't have this in the bundled version as of time I inquired with them.

Rather, it's a separate controller sold on its own. I.e. I purchased the CLOUDLINE S6 and then look for "AC Infinity Controller 67" which is the model that includes this PLUS new features - i.e. bluetooth and other features where you can even program schedules & alerts.

I just went to check my Amazon orders and can't find it when searching by name but I can get to my old link - but - it's showing as 'currently unavailable'. I'd inquire with them directly to find out the scoop - I did send an email to the address they suggested for feedback re: the newer features and never heard a peep back (disappointing customer support/service there). One thing I disliked was it wasn't really "secure" from tampering by anyone in range. That was almost a deal breaker for me.

NewGrower2011 said:

CONTROLLER 67, Temperature and Humidity Fan Controller, with Scheduling, Cycles, Dynamic Speed, Data App

Your source to create smart growing systems with components including advance grow tents, inline fans, clip-on fans, LED grow lights, and UIS™ controllers.

www.acinfinity.com

Click to expand...

My god you can even mix and match models. They finally did something right.

Thanks guys, great info here.
Unfortunately, I cannot afford to buy expensive ventilation setups with $200 fans, speed controllers and so on... Was looking for a ghetto solution to my problem.
Guess, there is no cheap way around it.

I just removed the exhaust duct fan together with the carbon filter and replaced them with a simple PC fan on the exhaust opening, just to see what will happen.
This immediately lowered the temperature in the box from 45 down to 38 centigrade in the direct light, which proves that my duct fan with the carbon filter wasn't moving enough air.

Now, I have grown without a carbon filter several times before, so I guess I can do this again, but the fear of getting caught and thrown in jail will always be there... and I just don't like living in fear.

Guerilla Kush said:

Thanks guys, great info here.
Unfortunately, I cannot afford to buy expensive ventilation setups with $200 fans, speed controllers and so on... Was looking for a ghetto solution to my problem.
Guess, there is no cheap way around it.

I just removed the exhaust duct fan together with the carbon filter and replaced them with a simple PC fan on the exhaust opening, just to see what will happen.
This immediately lowered the temperature in the box from 45 down to 38 centigrade in the direct light, which proves that my duct fan with the carbon filter wasn't moving enough air.

Now, I have grown without a carbon filter several times before, so I guess I can do this again, but the fear of getting caught and thrown in jail will always be there... and I just don't like living in fear.

Click to expand...

Then dont do it or move somewhere legal. Most of us on here are legal growers....

yeah, if you can't afford to play then you should look into other options. I'm in similar shoes and odor control/stealth are required - if I can't solve those two issues I just don't even consider it.

re: the AC infinity and mixing models that is another key thing - you can finally do the 4" intake/6" exhaust and similar setups. Finally! Once they realized what their target market demanded in features it was bound to happen.

I'm happy with my AC infinity t8 in a 4x4-I can't hear it on it's lowest setting but I went to a lot of Rage Against the Machine concerts in the 90s that really took the edge off of my hearing. It moves a lot of air, but I want the option to add a carbon filter and 8 more feet of ducting to vent outside during the summer. Big fan turned down is definitely the way to go.

NewGrower2011 said:

re: the AC infinity and mixing models that is another key thing - you can finally do the 4" intake/6" exhaust and similar setups. Finally! Once they realized what their target market demanded in features it was bound to happen.

Click to expand...

Yeah it took a while but im glad they figured it out. Really you shouldnt need an intake fan but I could see using one fan to cool a light and another to pull air out of the tent. Im just glad you can set a minimum speed. That was my biggest gripe. Lights of, 2. Lights on, 6. Thats what we needed.