This is my first grow actually trying to do correctly to increase the yeild. Prior grows I was just half-assing it.
Could somebody explain tent cooling to me please?
I don’t understand what’s needed or what size fans. I found this chart online that said a 16 cfm for a 2x2x4 tent, from there I didn’t understand if that’s the intake size, the extractor fan size, both? I know I don’t need filters, smell isn’t a issue.
My current cooling strategy is two fans and having every single port on the tent open along with the door. It’s not working lol
First always draw air from inside the top of the tent and exhaust out from there if possible due to the effect of hot air rising and cool air falling, Second if your running a carbon filter that’s gonna create a flow restriction so you have to compensate for that.
General guidelines lets say your running that sized tent or even a 2x4 or 3x3 and running Led lights with a carbon filter a standard 4" exhaust fan should do the trick but consider ones that have variable speed controls or even controllers like the AC infinity line.
Also “it’s not working” doesn’t imply what the issue is, i presume too hot but how hot ? and your fans what are they doing ?
Ultimately all one needs is an exhaust fan, and a definite bonus is a circulation fan within the tent itself.
Also if running led’s due to lack or IR heat from the light source we should be running at higher temps than old HPS guidelines of say 21C/78F and should be more in the 28-30C/82-86F range.
For tent cooling, and I assume you are on a budget, it is about air flow. You said odor is a non issue so simply, you only need to exhaust the tent at a reasonable rate. If your ambient temps aren’t too high or too low just run an exhaust fan (w/ an intake) so that the air is exchanged at a rate where the temp stays at a point that it is equal with the ambient air temp. As far as air exchange is concerned MORE is better. IMO, you only need “cooling” if you are running a closed system with CO2. Good luck!
Also a standard 4 in inline will typically exhaust a 4x4 sufficiently. But as I said MORE is better…you would probably feel most comfortable with a 6 in inline fan .
I think, when actively venting with a passive intake, one of the keys is the intake capacity needs to exceed the exhaust.
In my setup, (60”x60”x80” tent w/ AC Infinity 6” and Mars Hydro. FC-6500). I typically exhaust actively from the top and intake passively from the bottom.
The heat from the FC-6500 requires that I exhaust at high CFM.
I don’t know if it’s proper, but I use a 1:4 exhaust:intake ratio and my AC Infinity at full capacity still sucks the sides of the tent in.
I use ports at the bottom and actually have to use the top ports too for intake and run hose from those top ports to the bottom of the tent to create a bottom up airflow.
Close some of your intakes. you’re moving air around really, not venting the cabinet. Personally, I exhaust from the top of my tent, and keep a vent open near the bottom. Sure, cool air falls, but if its falling right next to the exhaust fan, you are circulating the top portion of the tent, and below that gets warm.
I want to think of the tent as a wind tunnel, fresh air enters the bottom and has no place to go but be sucked out by the exhaust fan at the top. Even with 2 x Viparspectra P4000’s in a 3x4 tent it doesnt get hot using a 6" exhaust fan, no booster / incoming fan, just an open vent at the bottom. If anything, I had problems keeping it warm in the winter in a 60F basement!!
I use two side mounted fans diagonally opposite from each other at different heights along with a rotating fan at the base to circulate within the canopy.
@Mr.Sparkle my issue is the tent being to warm. I have two small fans, one oscillates. They sit on the floor blowing on the plants. Both are on high
@Foreigner My temps are reaching 90° with the door cracked. Ambient temp in the room is high 70s. I hope it will chill out a little once we start running the AC
@smokenhike I have my tent in the dinning room which was converted into a little plant area. We all enjoy the smell of it
You can do a few things to cool your space better. First, pay attention to the flow rate of the coolers you are using, for your space according to the table you said you need an exhaust fan/fan that has a flow rate of 16cfm, to handle the air renewal in your environment. To do this calculation you have to multiply your width x length x height, to get ft3, which is the CFM, flow per minute.
Second, you have to position them at the top of the tent, as hot air has a tendency to rise, and that hot air is what you want to get out. I would leave the air intake passive, to generate a negative pressure inside the tent, which helps to reduce the temperature.
Another tip is to put one of your fans facing your quantum board, this will significantly reduce the operating temperature and consequently the temperature inside the grow.
Another way that when it’s very hot around here I usually do it is to put some bottles of frozen water inside the grow, it helps for a few hours, and the temperature reduces by 2/3ºC
You can also program your photoperiod so that the lights are on in the lowest heat period in your region, which will also help to control the temperature.
In a 2x2x4 tent all you would need is this fan (linked). I would run this fan outside the tent since that size tent is already fairly small and height would be an issue (I also have a 2x2x4). Set the fan up with a dust filter on it for intake on one of your lower ports to bring in your ambient room temp and passively exhaust the tent with a port at the top of your to remove the heat in the tent during lights on. Great option I’ve used in my short tents. Also a small humidifier to help keep your VPD( Vapor Pressure Deficit) in check with those higher temps. higher temps can be managed well if your VPD is in check. When I run a humidifier the temp difference is usually a good couple degree’s lower than running without. temps are a pain in the butt for us AZ guys and gals.
Hope you get this all sorted and everyone can shed some degree’s for you!
I had to work with what I had. The box fan is blowing air out from the larger port on top. The green fan pulls air in from the door when it’s cracked open. I need to do some wire management an adjustments. It has cooled it off a couple degrees so far
get a legit exhaust fan and hook it up as such or place that bottom fan up into one of your exhaust ports for the time being, circulating air inside isn’t gonna do anything other than evenly heat things up if your not exhausting out your hot air its of course gonna get hot.
I get working with what you have and being on a budget… if I were running what you are right here I would rig that smaller fan on the floor to exhaust from that top left port. remove the box fan from the tent and stick it in front of your lower open port(bottom right) and with that open space on the floor to the right of your plants put a big tray full of water and close up your tent to pick up your RH. also move your surge protector out side of the tent. anything putting off heat besides your lights would be better outside the tent and when you turn on your AC it will be that much better. Hope you can grow some serious Fire for your dad!
I wanted to come back to this topic to say my diy rigged up cooling (above) has been working well! I’m down from the 90s to low 80s. After closing the unused ports I was even able to achieve a vaccum. Thank you everyone for the information an help!
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% with what 
