Just wondering is a ventilation duct necessary for the grow process? And if so will running the duct outside during the winter time affect the plants?
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Welcome to the forum. Grab a seat ask a lot of questions.
Yes its absolutely necessary to air into the grow. Plants use oxygen and carbon dioxide. When there in enclosed spaces they use that up pretty fast therfore you must have fresh air. Going Into the grow and heated air leaving the grow. Its like having people in a sealed box there gonna suffocate and possibly die. Maybe not that extreme but they wont grow well. So make sure you set them up with some air flow. Where are you growing? Can you post a picture of the area? We can help make suggestions for you have a better set up for growing!
If you need to ask some one something use the @ symbol before the name that gives that person a notification and when they log back in they can see it and respond.
Oh and blowing air out into winter is ok. Do not blow winter into the plants area unless its the right temperature. Cannabis likes certain temps, and no cold air below 72 degrees until the last bit of flower.
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Hi @mmcarter24
Welcome to GN and great to have you here. As above movement of air is essential, fresh and cool air is important below the canopy of leaves and removal of hot/stale air above the lights. A good thing for you to start with is to try our GN University. There are some great courses, I would suggest starting with the free cannabis 101 course and it will answer most questions you probably have. If you have any questions though, please feel free to ask.
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In a grow tent that has holes for ventilation and I have a fan in the tent and a humidifier running in the room where the tent is. Just no duct leading outside.
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Also I have a temp and humidity gauge humidity stays around 50% and temp stays between 75 and 80 and degrees. So far I keep seeing that the duct that ventilates the air OUT is just to reduce the strength of the smell which is not a concern for us so I wasn’t sure if it was a necessary component if it’s only purpose is to ventilate smell out. Thank you!!!
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If you’re not worried about the odor, you still need air exchange in the grow area. Plants consume CO2 so if you don’t have air exchange they won’t get what they need. Unless of course you’re adding CO2 to a sealed area. 
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So I can use something like proCO2 inside the grow tent instead of using a ventilation duct? Or the ventilation duct is needed in the grow tent even if I’m using a product like proCO2?
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All C02 does is provides the leafs with what the plant needs for Photosynthesis. I use Exhale bags slightly above the plants, C02 is heavier than air. Even a small amount of C02 will help the plants.
You need to use ventilation to prevent mold and other nasty things that will destroy your plants. Exhaust fans with a controller will help with air exchange but will also remove the C02 at the same time, having a controller set to turn on and off will let C02 build up, then remove it along with heat and humidity that build up and triggers the exhaust fan. Unless you have a carbon filter connected to the exhaust fan it won’t do anything to reduce smell.
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You are the man 
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check into lung room to get warm up humidity fresh air into your grow room .
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It would probably be best to still have some vent tube taking the old hot air outside or to a basement or crawl space an attic ECT and then the fresh air going into tent can come from the king room the tent is in now. But u’ll wanna get the old air ducting out of the room so u r not sucking back in the old air u just removed if this makes sense. Also if it is photo plants ur gonna want to get a way that light don’t come into the tent during the dark hours or it will cause u issues. Have u ever grown tomato ola ts with success?? If so then these r almost grown the same way but with weed plants one takes a bit more caution and does a bit more work to have better outcomes at the end. Next year play with tomato’s in the garden and do training and defols like u would a por plant and watch the rewards at the end with the tomatoes also.
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I used to use the exhale bags and I have noticed not having them the buds do tend to be smaller and less covered in tricks. I always had my bags under the canopys this way as the exhaust was sucking air out from top it would pull the carbon dioxide the bags released up into the leaves before it got exhausted. I felt that the leaves blocked some of it from just being exhausted right out the room.
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There’s no way to “avoid” a constant air exchange that’s needed and necessary… Imagine putting a plastic bag over your head and having only a few holes, none near the mouth. That’s what the plant experiences. Clean air in/ out is mandatory.
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