Ventilation Help

Ok so I have a 3 foot length by 5 foot tall grow tent and I was wondering if 2 6in 260CFM duct fans would circulate enough air as well as keep it cooler. One would be exhaust with carbon fillter on it at the top of the tent(inside) and the other at the bottom blowing in cool air( if it's a good idea anyway). I'm using a 400 watt hps with a winged reflective hood. I am also going to be putting 4 autoflowers in the tent. I would just like to know if I need something more powerful on the intake or outtake of my air circulation to keep things cool, have fresh air and keep the RH down as well.

That should work well. pretty low roof on that tent though. Can your 400w hood be vented?

Should be good with that.
If your hood CAN be be vented, use one fan for that and the other for your filter.
A passive intake is all I normally run on all my tents.

Damon Elder said:

Ok so I have a 3 foot length by 5 foot tall grow tent and I was wondering if 2 6in 260CFM duct fans would circulate enough air as well as keep it cooler. One would be exhaust with carbon fillter on it at the top of the tent(inside) and the other at the bottom blowing in cool air( if it's a good idea anyway). I'm using a 400 watt hps with a winged reflective hood. I am also going to be putting 4 autoflowers in the tent. I would just like to know if I need something more powerful on the intake or outtake of my air circulation to keep things cool, have fresh air and keep the RH down as well.

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Are these 260CFM inline duct fans?

Or 6 inch BOOSTER fans that actually run @ less than 1/2 that speed, unless connected to a closed system w/ a real fan?

2 things in growing not to ever skimp on.... Air. Light. You can always turn both down if its too much, you can't un-fuckup the plant when it was baked, sweated, and/or starved for light....

Get a 6" 400-460cfm REAL fan.... Anything under 400 for a 6" is bullshit, read the WHOLE box, even the small print, you will find the CFMs it claims are not its standalone CFM rating....

Pleaseee

I have a similar setup, 3x3x5 tent, 400 MH inside a cool tube with side reflectors right now. But only one 260 CFM exhaust fan. I do have and intake fan in the window blowing in cool autumn air and I find it ends up getting too cool sometimes at night (early 70s), have to turn the power down on my exhaust. In the summer when temps were 90F outside I did have to run an A/C and an intake fan at the bottom of my tent in front of passive vent. As long as your fan has a potentiometer (speed control) you should be fine.

Thanks for all the feed back guys. My light can't be vented though as it is just an opened ended wing with the light in the middle. I could tape ducting to one side with a fan sucking air out right behind the light if that would help any? But where I was going to put the carbon filter and hood, one open end of the light would be facing the filter and basically be pulling air from the light and tent and the other side of the hood would be a couple inches from the side of the tent. Just trying to decide if I need to spend like a hundred on fans or over that amount. Right now I'm looking at about a hundred for ventilation.

I would get 2 6" vortex inline fans. Set one up attached to a carbon filter inside the top of the tent to draw out the heat. You can put the fan either inside or just outside the tent doesn't matter. Then set your other up as an intake on the opposite side of the tent and on the bottom. Get some good quality speed controllers for both fans in case you need to adjust speed to help with humility levels or temps.

The speed controllers I'm talking about are expensive. Bought mine on Amazon but hey are the ones to get. Over $60 maybe even more cant remember.