Hey guys, I wanted to get your thoughts on a ventilation question. I have always used an exhaust fan, but stuck to passive intakes. I was recently gifted another in-line fan of the same size. Should use the new one as a intake fan? If I do, does that mean the exhaust fan will have to be running all the time? Because if the exhaust fan is set to come on based on environmental triggers, I wouldn’t have constant negative pressure.
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You should keep the exhaust fan on 24/7 to exhaust the stale air and keep the RH in check. An intake fan is a nice addition as longs as the air you’re bringing in is cooler than the tent or grow space temps 
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I agree with @OGIncognito I run 2 of the 4inch exhaust fans one I run 24/7 and other is ran with light timer just for extra heat removal my lights get hot at 100% and have 1 intake fan running 24/7.
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Hmm. I’m my tent is in an uninsulated shed. It tends to get very too hot where I’m at (Maryland, zone 7b). I did invest in a portable air conditioner, but with the shed not being insulated I’m not sure how effective it’s going to be.
My tent is 5 feet high and sitting on a 3 foot table. If I ran an intake fan, I would probably put it on the floor where the air is a little cooler so I guess it’s probably better than nothing? I dunno, do you think it’s worth the added electricity costs and the cost of buying a new carbon filter, or should I just stick to passive intake? My biggest concern with the passive intake is light leaks.
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Oh I see. So you’re just relying on passive air intake? That’s what I’ve always done (except I only have one exhaust). I’m concerned about light leaks from having to have the flaps open though. I got this extra fan for free and just wondered if it would be worth it to add. I would have to buy a second carbon filter. Not a huge deal but if it’s not going to make much difference I don’t want to waste the money.
It may not be worth it. The temp in my tent is going to be similar to the temp in my lungroom (a shed) which is going to be similar to the ambient outside temp. I did buy a radiant oil heater and a window air conditioner, but with the shed being drafty and uninsulated, I’m not sure how much it’s going to help
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Sure a carbon filter for the intake fan would be a waste of money…
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Really? I’d be worried about the fan sucking contaminants in and blowing them into the tent. It’s dusty as hell in my shed
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Maybe cover it with a sock?
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lol that’s not a terrible idea. I can’t think of why it wouldn’t work. Anybody have any feedback with this idea?
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I use passive intake but I don’t use the flaps, I use the both of the 6 inch duct inlets and have duct hoses hooked to both that utilize a couple bends and covers (towels) to prevent light leaks. I also have Leggs (lol, panti-hose) over the ends of the ducts to keep out the contaminants. 
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If the outside air is hotter I wouldn’t use the intake fan, I wouldn’t use the carbon filter until it was absolutely necessary, it restricts the air flow slightly and only used on the exhaust fan to filter the smell
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That’s not a bad idea. Might make sense to do that and put a little desk fan there to push some air in.
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The would imagine the air in the tent would be hottest, simply because of the lights. It’s LED but it’ll add some heat. The Lungroom should hopefully be cooler than outside, assuming this portable ac helps at all
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I use pantyhose and have a bend in the line in to prevent light leaks
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They have screens on Amazon that slide over the 6 inch duct. But your idea is slick never gave it a thought.
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