DIY Cool Tube: Draw air from the grow chamber or from a separate intake?

I searched but could not find, so I'm asking.

It's an office cabinet, 2x3x6 in which I will be using a separate carbon scrubber with a 206 CFM fan blowing out the top.

For the cool tube, I have a 160 CFM booster fan to cool the 400w HPS but, should I leave the duct open-ended and draw the air from inside the cab, or should I run it to an exterior intake and seal it off from the cab air? Ambient house temps are between 60 and 75 degrees.

Thanks for any/all help.

PS If it makes any difference, the mother/daughter chamber will not be part of this cab.

if you have a seperate fan and carbon filter then draw in air from outside and back out again

That's what I was thinking (really!), Warrior. Thank you for confirming.

I did a closet grow once and I had the cool tube pulling from within the grow space. I had 2 intake vents down low which was good for strong air exchange. The temp stayed down and everything, however, the amount of air that was ripping through the space was extreme, violent almost. Therefor I would suggest pulling from outside the grow space. Just my 2 cents, good luck my friend.

If you draw air from outside the grow space you will not need a carbon filter on the light cooling circuit. If you draw air from inside the grow space, the air will need to be scrubbed. Personally, I prefer to cool my lighting with outside air. Most of the time the outside air is cooler than inside (cooling the lights better), and it avoids another carbon filter. Also, if you ever install CO2, this is how you will want to be settup.


https://www.rollitup.org/indoor-growing/407048-20-000-watt-medical-grow.html