Ventilation( smell) issue

Hi, I have a 39"x39" x80’ tent. An 90cfm inlet fan and a 440cfm variable speed exhaust. on my first grow(2 Plants) I had no smell. I used a think crucial carbon filter. ventilation worked well. on my second grow( 3 plants) I can’t get rid of a residual smell. I have changed the filter twice with no change. Once with an ipower filter ( used both ends) and a think crucial filter. any ideas what to check next. thanks

Couple things I would check…

  1. Is your tent under negative pressure condition?

  2. Check the connection from your fan to your filters, if air leaks though there it won’t be filtered.

  3. What is rh in your tent? If it’s too high the filters won’t work well.


fan is under neg pressure. I have taped around fan/filter connection to seal. humidity has been 30-60%.humidity is very low here in winter, had to add a warm mist humidifier to raise humidity.

Where are you discharging exhaust to and so tou have fresh Air entering room that tent is located in
And i dint mean from outside just air exchange over all ??
You filter and fan set your should be more than enough for you tent size

exhaust goes back into the same room. only outside air comes from opening a door, probably very little air exchange in the room where my plants are. i will get some air movement outside the tent and see how that works. thanks

Try that @BobD1 i use the ipower carbon filters with my inline fans no smells what so ever
also run exhaust at half speed
I have 4x4x7 foot tents and recycle my air as well
Soes it smell when you tents are closed or only when you open tent ?
I actually had to install a carbon filter in my grow room cause every time i opened tents the room would smell


smell is all the time now. everything was working fine with smell only when I opened tent. I could even keep smell down with tent open if I turned the exhaust on full. haven’t got to exchange air yet. was going to get 2nd fan and filter for back up.maybe I will get them now. thanks Countryboyjvd1971

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Sure thing buddy if you need me tag me add @ symbol in front of my user name nothing before or after like this @BobD1

Hey bud​:wave::wave: Question for ya… I have a infinity t4 in-line vent (128 cfm) on high. My tent is a little over 7’ tall and 4x4. In set-up phase at the moment. I thought that 128cfm was going to be risky for odor control with 4” ducting so I decided to go with an infinity t6 with 6” ducting instead which is about 351 cfm give or take. So I essentially have the same system in 4” and 6”. And 2 ipower carbon filters 4” and 6”. I was thinking about returning the T4 but now I’m thinking about it a bit more… My room is not close to a window or fresh air. Perhaps I should keep them both and use the t4 to blow fresh air into the tent and t6 with carbon filter to exhaust. I will be exhausting into another room. Will it smell in the other room after it passes filtration? Odor for me is a biggie! What do you recommend? I think it’s safe to return the t4 carbon filter??? Your thoughts ?

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@Mendax welcome to the forum
that’s exactly what I do in my grow room
I recycle my air into basement and carbon filter each way

I have a 6 inch exhaust and 4 inch intake same fans that you have and get good results With no Oders

So I’m on board with you line of thinking keep prefikter clean on intake and exhaust and I think you’ll be happy
Love the control you get with the infinity fans

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Hey bud, thank you! That’s funny… :joy::rofl: same exact setup… yea, the control is awesome and I love how quiet they are too… Big plus. So just to be clear, you have a carbon filter on the 4" providing fresh air to the tent? If so, that filter is on the floor, inside the tent correct? And the 6" hung on top?