Which fan size for better airflow?

[Takatankata]

Due to a stroke of luck I found an affordable tent. Ordered a 60x60x180 but received an 80x80x180. In hindsight I should've gotten a rectangular one, oh well, I got a tent.
Now I have a Carbon filter (260m³/h) attached to a 125mm (2-speed 187/240m³/h) and 100mm ducting dumping the air out.
I'm now wondering what size fan I'd need to supply an adequate amount of air into the tent, because right now I'm using a tabletop fan which I'd rather use elsewhere in the home and it forces me to keep my tent open for longer periods of time, negating the point of the carbon filter.


Would a clip-on fan in front of the lower opening be enough or do I need one for supply and a 2nd one for airflow?

 

[Shugrows]

I pretty much always have 2 one on top blowing down. Then one down low the opposite side right above the pots. Dont wanna blow directly on the pots as it will make them dry uneven. This goes for all my tent. My biggest to smallest.

 

[BII]

Why to you think you need a 2nd booster input fan for this small tent (6.25 sq. ft; 43 cubic ft.)? You already have a 100 mm/4 inch exhaust fan (pushing out >8400 cubic ft./hour = >140 cubic ft./minute). That should be enough to suck in and push out sufficient 'fresh' air even with resistance from ducting.

Rather, you need to plan for temperature control as the no. 1 ventilation priority! And secondarily, you also need 1 or more fans for internal air movement [such as consider the AC Infinity speed-adjustable oscillating fan; but clip-ons, desk or other cheap fan(s) will work well].

How do/will you get rid of heat from the light(s) you'll be using? Does/will your exhaust fan have ducting to exhaust heated tent air to the outside? Are/will you be using a thermostat to control the exhaust fan? If it's hot where you are, how will you cool the tent's environment (it's input air) -- is the tent within an air conditioned room?

Also with such a small tent, presumably for 1 or 2 plants, you may not or rarely need the carbon filter. [I have a tent about double your size, 2.5 x 5 ft./12 sq. ft. and haven't used/needed a filter for years]. I suggest just patch it in only when actually needed.

 

[Lil Dab]

Due to a stroke of luck I found an affordable tent. Ordered a 60x60x180 but received an 80x80x180. In hindsight I should've gotten a rectangular one, oh well, I got a tent.
Now I have a Carbon filter (260m³/h) attached to a 125mm (2-speed 187/240m³/h) and 100mm ducting dumping the air out.
I'm now wondering what size fan I'd need to supply an adequate amount of air into the tent, because right now I'm using a tabletop fan which I'd rather use elsewhere in the home and it forces me to keep my tent open for longer periods of time, negating the point of the carbon filter.


Would a clip-on fan in front of the lower opening be enough or do I need one for supply and a 2nd one for airflow?

My 5'x5'x80"I run (2) 6" inline fans with carbon filters exahausting air and (1) 8" inline cheap duct fan with no filter as an intake. Intake only turns on when RH gets high the exhaust controls temp and rh. Then I have 2 oscillating fans moving air around the tent. I have run the bigger tent passive too and it worked fine rh did get borderline during flower in a pack tent though so I've added the intake fan

My 3'x3'x72" tent runs (1) 6" inline with carbon filter as an exhaust and just use the mesh vents as passive intakes. then I have two fans in the tent moving air around

 

[Takatankata]

Why to you think you need a 2nd booster input fan for this small tent (6.25 sq. ft; 43 cubic ft.)? You already have a 100 mm/4 inch exhaust fan (pushing out >8400 cubic ft./hour = >140 cubic ft./minute). That should be enough to suck in sufficient 'fresh' air even with resistance from ducting. You need to plan for temperature control as the no. 1 ventilation priority. And as noted you also need 1 or more fans for internal air movement [such as consider the AC Infinity speed-adjustable oscillating fan; but clip-ons, desk or other cheap fan(s) will work well].

I thought a tent generally needs a fan to push/suck air into it and another one pulling/pushing air out. I didn't think the exhaust fan would be sufficient enough. I mainly bought it to combat smells, not really as a cooling solution.

Not mentioned: How do/will you get rid of heat from whatever light(s) you'll be using? Does/will your exhaust fan have ducting to exhaust heated tent air to the outside? Are/will you be using a thermostat to control the exhaust fan? If it's hot where you are, how will you cool the tent's environment (it's input air) -- is the tent within an air conditioned room?

My exhaust fan has ducting which dumps the air into the room in which the tent is standing, I don't have the possibility to directly vent it to the outside world. The room itself is relatively stable with peak temperatures currently being ~23C/73F and doesn't have A/C (German A/C is open windows at night), coming winter it should peak at ~19C/66F
I didn't consider temperature control at all because inside the tent it's a very stable 23C with light off and 26C on (28C/82F without running fans). I'm mainly concerned about the high humidity and thought a proper or rather complete "professional" setup could keep it at bay.

I have to admit that I was a little confused at first why you'd mention climate control, makes a lot more sense that all these things link together, oops.

 

[Lil Dab]

thought a tent generally needs a fan to push/suck air into it and another one pulling/pushing air out. I didn't think the exhaust fan would be sufficient enough. I mainly bought it to combat smells, not really as a cooling solution.

Most the time using the mesh vents and just exhausting the air is plenty sufficient. Most folks I know run passive tents the biggest concern is air moving in the tents with circulation fans

I have to admit that I was a little confused at first why you'd mention climate control, makes a lot more sense that all these things link together, oops.

Lots of the newer fans come with controllers that turn the fan on and off according to temp and rh. I use AC Infinity controllers and fans in all my tents the fans turn on when temp and RH go over my settings 80F and 60% during veg and 50% during flower

 

[Takatankata]

Most the time using the mesh vents and just exhausting the air is plenty sufficient. Most folks I know run passive tents the biggest concern is air moving in the tents with circulation fans

Good to know. Saves money and hassle

 

[BII]

Regarding "I thought a tent generally needs a fan to push/suck air into it and another one pulling/pushing air out.:" Keep in mind, the same amount of air that is being exhausted by your fan is at the same time being sucked in (that's what the screening/vents on the bottom of tents are for, with these not made for fan attachment). I presume the most common set up, particularly for such a small tent, is a single exhaust fan. For ex., I don't recall ever seeing ads for tent intake (vs. exhaust) fans.