Hey everyone one my question today is I'm getting a 3x3x78in grow tent

I’m looking at a virtual sun 400 watt hps/mh grow light with cool tube so I’ll need an intake fan and duct work for that but I also want carbon filter where does it all go!!!

your tent should have openings for the ducting. usually velcro flaps.
your carbon filter should go on the exhaust side of ventilation.
you may consider a hepa filter for intake side.

ive seen lots of ways to set it up though. it takes some tinkering based on your environment.
currently, in my tent is a 1000w air-cooled, double-ended light. i have a fan on outside of tent that is connected to light via ducting.

so the cool air (from outside my garage) goes:
in fan> in light> out light> out of tent>

  • i have a second fan that just pulls warm air from tent and exhausts it outside.

but my friend does it different because he only has 1 fan:
he uses exhaust side of fan,…to pull warm the air that is inside tent and light, through light and out through fan:
warm air> light> fan> outside somehow…

like i said, based your specific conditions and, the gear you have available to use. you just gotta make it work.

I’ve been doing some research and it’s all quite confusing!!! Maybe a better ? Is do I need two fans one to cool my virtual sun 400 watt hps an one for a carbon filter

The light will need a 6 in fan and ducting but unsure what I need for carbon filter 6 in also???

How do you have your exhaust fan vented

well, again. depends on your situation.
a 400W light wont produce crazy amounts of heat. but without venting, it will get up to 90 or so.

ultimately, yes.
1 fan to blow cool air through light system in a closed-loop fashion i think would be ideal.
but that will require a 2nd fan. to exhaust the air the light heated up.

even though the cool air though light will reduce heat output, it wont eliminate it.

if the opening on light is 6". then yes. you want to match that with fan/filter/ducting.

my exhaust fan sucks warm air from inside tent…pulls it through fan via ducting…through fan and out of garage via ducting. i made a 6" hole in wall to vent it outside.

but again…all of this might be overkill for your situation.
1 exhaust fan could very well be enough to pull warm air out.

is your tent going to be located in a cool area?
are you able to install ducting that leads to outside?

I’m gonna put it in my bedroom closet only place to vent would be the attic I have a window but that wouldn’t be very lowkey. I’m in South Dakota and people would not approve

considering the time of year it is.
you can most likely get away with 1 fan. and if it is required by warmer time of year, you can add 2nd fan perhaps.
venting it up into attic is not a bad idea.

i doubt you can get cool air from attic…so when your exhuast fan pulls air through light, and up into attic…it will draw fresh air in from wherever it can. like the bedroom…so the temp of bedroom will be a factor also.

i have a very similar setup in closet of bedroom. not my tent setup, but a 2nd location i use for only veg’ing.

for that setup, with a 400W MH light. i have only 1 cheesey 4" fan. it is connected to duct that leads to top of light. and pulls warm air from light out through duct and outside (in your case into attic).
but,…the bedroom temp stay at 75. so the air being drawn in doesnt need to be cooled down. make sense?

in the end, you want the temps in tent to be stable in the mid-70’s. if you can control the temps around tent…it will aid in controlling inside.

Thanks a lot can the fans for the lights and carbon filter go on outside of tent? I haven’t got anything bought yet having trouble with my seed order so kinda waiting for that to be resolved before I pull the trigger thanks for all your help

yes. its better to have fans outside.
the filter can go anywhere in-line, of exhaust side.

To give you an idea how it could be setup with 1 fan pulling air out through the carbon filter and light here is how mine is.

Exactly what i would’ve suggested since the heat from a 400w is easily managed