I thought I set my Tent up great.....

Hi RIU,
I did lots of research and asked lots of questions.
My flower tent is running 10 days
Lights on;
82-83 degrees
53% RH
lights off;
74-75 degrees
56% RH
WATTAGE
400 HPS
180 CFL
580 total

Ventilation out
>> carbon filter >hard duct> fan 400 CFM 6"> soft duct > hood > out of tent.
Ventilation in
160 CFM 4" fan with filter blowing in cool room air.

My problem is positive pressure, my tent looks like a ballon.
I put a fan controller on my fresh air input fan but as I turn it down the temp rises quickly.

I thought I did a pretty good job, now I read about another way to duct a tent.

A photo of my current setup is below.

I can't get negative pressure with my current setup without overheating the tent.

So I see a thread point another Noob to a high times thread about ventilation....

It makes a ton of sense that mine is done wrong.

they say take fresh air in the fan thru the hood and out.
set up your filter with a second fan drawing thru filter and out of tent then use a passive air inlet.

Voila negative pressure!

So should I change my setup?
will I get much lower temps by NOT drawing thru filter before pushing it thru hood and out?

If I am use my 6" fan and draw in fresh air and pump it thru the hood and out of the tent.
Then re task my fresh air input to draw air thru my filter and out.
Then I need a passive air intake.

Will I see a big difference in Temp in my tent if I change my current setup??

INPUT Please!!

I have a 600 watt that I would love to put in my tent, I just never thought I could handle the heat load.

Thanks for Reading!

My tent is 3x3x6

Remember every time your ducting is bent you lose cfms and with all that bunched up your probably losing a hefty amount. I would try and find a way to run it as straight as possible in this order carbon filter/reflector/fan exhaust from tent. You could also try and relocate the exhaust fan outside the tent for more room.
Hope this helps

Sorry accidently posted the same thing twice lol my bad

yeah, I'd have to agree that your exhaust fan should be outside your tent. Try carbon filter>soft ducting>reflector/hood/light>soft ducting out of tent>exhaust fan.

I would get rid of the intake fan for 1 then hook the exhaust fan on the other side of the light so you are sucking through everything.... always put the fan last imo. I would put the filter where the exhaust fan is and the fan between the light and exit port... how you gonna run 400 out and only put 160 in. I run a 140cfm fan and filter in a 2.5 x 7 x8 with a magnetic ballast in the room and a 400w it rins 5 degrees warmer than the room I suck air from.... whats the temp of the air your suckin

...here's a thread that will explain it way better than i can, ...one thing i'd suggest is that your intake fan is working against you and if you just eliminate it and go with passive intakes that should give you negative pressure.

Ventilation 101

...here's another one that may shed some light on your situation, as it were.

Benefits of Vertical Growing

peace, bozo

Hi Thanks to all.
@ Bozo, that's the article/ thread I read that started this whole thing.
You hit it on the nose!

How would you support the exhaust fan outside of the tent?

I agree I have lots of bends and they ruin CFM flow.
I just don't feel like making the change while I have a plant in the tent.
Its only 11 days and the 83 degree temp is acceptable if not a little high.

When my plant finishes Flower I will tear out my ventilation and redoing it.
I still have no idea how to support a fan at the top outside the tent?


does this sound like a good way to upgrade?
my new configuration.

4" duct from outside> hood> 4"-6" reducer> 6" inline fan 400CFM> 6" duct out of tent.
(my hood has 4" ports)

16"x6" carbon filter> 4"-6" reducer > 4" hard duct> 4" inline fan 160CFM> 4" duct out of tent.

a hard duct passing thru a low vent as a passive air inlet.


thanks for all the input!

Would anybody lose the reducers and switch the fans?

would the 4" 160 CFM fan Be able to cool the light hood if it is a straight run with fresh air from outside tent??

I do not think my roof brackets could handle Any more weight....
So my fan attached to filter will have to sit below my tray and the duct will have at least two 90's

Why do you use reducers? The filter should be able to go right into the fan if you toss that ducting.

It would be easier to buy an axial fan (6"-230cfm) and use it to cool the light all on its own and use the carbon filter for exhausting the odors. By doing this, you can relocate the large fan and filter off the roof of the tent and save you the possibility of a crash and burn. I grow in a closet and have that exact setup. I pull in from the garage, through the light and into the attic. it will take a lot of the heat load away from the tent. I then have my filter/fan setup pulling a wee bit of negative on the room, and all is well.

Using the same fan to try and do the light and the filter is a pain and has tons of restrictions unless you have ample room. Try it and you will see an epic difference in the whole environment of the tent.

Peace and Great Grows

Asmallvoice

I have seen a setup where the filter is outside the tent and just resting on the ground.

I bought my my hood and it has 4" inlets, I had the 4" inline fan 160 CFM drawing a loop in another space.
i bought a second fan and it was 6" inline fan 400 CFM, I put the strong fan drawing in thru filter and pushing out thru light.

fir3dragon said:

Why do you use reducers? The filter should be able to go right into the fan if you toss that ducting.

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