Venting during dark time of flowering

Should I keep my fan running at night for CO2 or plug it into the same timer as the lights? Will odor answer this question for me when flowers start? Now the closed tent is fine for odor control in my basement.

I run lights and extraction fan at the same time… your humidity will raise during lights out… so you may want to run your extraction fan for 30 min every 3 hours to get the moisture out… but it really depends on where you live and grow…
I have an ac unit that is set to a certain temp and it seems to keep my humidity in check when lights out … which is during the hottest part of the day… :wink:


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I have a dehumidifier running so that is not an issue. I have a small tent with 4 plants that are all very healthly. This is my first grow so I am excited so far. I think I will just leave my fan running 24/7 to keep humidity and CO2 managed. I don’t think I will wake up every 3 hours to run the fan but may buy another timer to run it so I can make my carbon filter last longer. Thanks for your input!!!


I personally leave my fans running 24-7
All my fans that is


I leave my fans running 24/7 … not my extraction fans tho…


Always more then one way to control the environment :peach:
I keep Ac running in flower room and dehumidifier so I actually recycle the air from flower room back into my basement
I see no sense in exhausting cool dry air just to recool and redry the incoming air
I keep a dehumidifier im the main part of my basement set to 50 % humidity
And set the one in my flower room to 40 with 74 degree temps :wink: my intake in filtered and exhaust is aslo
I averaged 76degrees with 40-42 humidity
I pay the electric company enough so it helps keep costs down in my case
Winters i dont need to run ac or dehumidifiers


Curious, why to you filter incoming air? Everything else makes sense but you are growing on a much larger scale than I am. Currently have 4 plants in a 2x4x6 tent for personal use after multiple back surgeries and chronic pain. Scrog the 4 under 600w light and I expect to only need 2 grows a year assuming my grows are productive. I am optimistic as my plants are exploding now that I started flowering and appear very healthy. On an unrelated topic, is a 3oz dry yield unreasonable?

You don’t need to filter intake air unless you’re in a dusty environment like I am. I just use filter material to keep the dust out of the grow rooms as much as I can.