1st timer. exhaust/vent help

Hello everyone!
This is my first attempt at growing, so here is a list of what I'm working with:
3' x 3' x 6' grow tent
400W MH/HPS with an air cooled hood
6"/400cfm fan with carbon filter **I know it's a lot bigger than what I need, but it has the adjustable speed controller**
My question is about the air-cooled hood and the filter...
I have seen some people attach the filter and fan directly to the light and then exhaust it out of the tent... Then others only used the filter to exhaust the air out of the tent and then they use a specific fan only for the light...
I assume the size of the room would have something to do with it???
With my size tent, which is the preferred way?
Thanks in advance!

Rufus the 13th said:

Hello everyone!
This is my first attempt at growing, so here is a list of what I'm working with:
3' x 3' x 6' grow tent
400W MH/HPS with an air cooled hood
6"/400cfm fan with carbon filter **I know it's a lot bigger than what I need, but it has the adjustable speed controller**
My question is about the air-cooled hood and the filter...
I have seen some people attach the filter and fan directly to the light and then exhaust it out of the tent... Then others only used the filter to exhaust the air out of the tent and then they use a specific fan only for the light...
I assume the size of the room would have something to do with it???
With my size tent, which is the preferred way?
Thanks in advance!

Click to expand...

Pull through the light

I'm sorry man! Can you explain that a little more?
In other words, should a fan be mounted to one side and pull (not push) the air from the other side directly throughout the light hood? (Like a straight line)
And then run the inline fan with the filter by itself and vented out the top?

Are you exhausting by bringing in room air or outside air. No matter wether you push or pull use the light attachment for one side of the vent system. Are you concerned about smell? On a grow tent you can pull in outside air from an outlet in the wall in to the tent . Put the blower on the outside of the tent attach the flex duct to the light and into the blower and out. Put carbon filter in outlet side if needed.

It will be just the air from inside the room coming in from the bottom.
As for the smell... I would love not to care, but my family comes over often, so, that is definitely a concern...
As for mounting the fan, and/or filter outside of the tent, I would prefer to keep everything inside it if possible...
I know I am making this more complicated than it should be, but I've always been a visual learner! And, I really appreciate your help, but can you elaborate on this sentence a little more? I don't understand the route you are explaining...
"Put the blower on the outside of the tent attach the flex duct to the light and into the blower and out."

Is your light set up with duct attachments or say 4inch ? Put the exhaust fan in the tent. Attach intake duct in floor to light set exhaust to outside. Pull air from light and tent at the same time position low so air travels from light down across plants up and outside intake vent from flor to light. Blower on floor behind plants on stand bolted. Vent from discharge of blower up and out
Most high pressure sodium lights have duct attachments on them.

Well! I'm still not fully understanding what you're saying!
I just set everything up to get a better idea of this and, now, I think I made two mistakes....
1 - I underestimated the light, fan and filter.
2 - I overestimated the tent.
I, more or less, have too small of a tent...
The way I wanted everything inside is not an option, so I will definitely mounting whatever I can outside of the tent...
If you/anyone else has pictures of the best way to set this up, I'd appreciate it if you could post them!
Tomorrow, I will do a little more research and add some drawings of how I might set this up... maybe then you can give me the best option...
I'm sorry about all of this, but like I said, I appreciate it!

If you have room for a 4 x 4 tent, I would suggest upgrading to one. Your light, fan, and filter will be a lot easier to configure. I just set up two, and I hung the fan and the filter at the rear of the tents and the light in the middle. Ducting coming from the filter and fan going thru the light and exhausting to outside. Pretty simple when I finally figured it out, and seems to work perfectly.

Maybe this will help-


With this configuration, you scrub the air in the tent through the carbon filter before it gets exhausted out of the tent (no smells leave the tent).
Also, you use the same filtered air to cool the room by running it through the air cooled light hood and exhausting the heat out (as clean smelling warm air).
No fan in the inlet, just let it cool the tent passively as the exhaust kicks on, it will create a negative pressure in the tent. Naturally pulls in the air from outside of the tent inside. Be warned though that your tent can only stay as cool as the air it is pulling in through the inlet. That means if you are exhausting your hot air from the tent into the room, then pulling in the same air you are exhausting....eventually your room is going to get warm and your tent will too unless you keep temps in check in the room. Hope this makes sense.

Yes!!! That's what I'm talking about!
Now, to suppress my OCD, are there any advantages / disadvantages of that set up as opposed to ONLY the fan and filter vented out of the top and then the light having its own fan blowing through it to cool it off?
For this little ass tent, does one set up have an advantage over the other?
Oh, and it will be vented through the ceiling - into the attic.
Cindysid - if only I could! I just got the damn thing a few weeks ago and hate dealing with returns and all that type of stuff! Oh well... live and learn! I guess this is a decent starter system... I plan on growing autoflowers for a bit to get some bud on hand and then I'll get into the reg's...

Yes, the advantage is only using 1 fan to vent, intake & scrub all from 1 fan. Less power consumption & less noise. Plus less equipment inside the tent leaves more room for the garden. The fan takes the heat from the tent and the lights through the same exhaust outlet. Not sure why you would want another fan in the mix other than to circulate ambient air in the tent.

Simple enough! Thanks Red!