I’m a novice cannabis grower at best and I’ve only ever grown in closets a handful of times. However i am currently the proud owner of a grow tent and all that entails. I’ve noticed on the tent there are a series of rectangular vents for air flow at the bottom of the tent. My question is how does one use these vents in flower without a light leak issue and what is the best way to position the external flap. I’m thinking about affixing a piece of heavy black plastic over the inner part of the vents so it would swing open and closed depending on whether or not the fan is on. Would love to hear what the rest if you are doing for this.
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I had a spare 8" port on my tent so I ran 5 feet of 6" flexi duct through it to a surplus cardboard box that I had cut out a section and attached a furnace filter to.
This gives me an airtight, light tight filtered air source for the tent.
Cheers
G
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For me, it depends on the environment in the tent I am trying to create, but mostly with mine anyways, open the vents and stick the corners only closed allowing the centers of the sides and bottom to stay open a bit… and adjust from there…
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I’ve been blocking any light leaks with an air purifier replacement carbon filter cut to size for the vents both in and out ~ along with cupping the flaps on the outside.
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Doesn’t that cause a light leak issue in flower or are you closing at lights out?
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I really like this idea. Less permanent than gluing plastic to my tent.
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In the next couple of weeks I’m going to be making cardboard light baffles (possibly lined or sprayed matte black inside) that will either set or velcro over those openings. I decided doing that was cheaper than rigging some kind of high cfm bars or something, and wouldn’t restrict access.
I calculated the area of the 6" opening my fan pulls through, and I’ll be sizing them based on that so it splits the intake air fully between the 3 vents. Is this necessary? I have no idea! On my first (and only so far) run, I had the back of the tent against a wall where it wouldn’t get light from the sides and I just left the back one open. The sides of the tent still sucked in more than I would prefer. So we’ll see!
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I made light baffles out of dollar tree supplies.
I’ll see if i can find a pic of my build.
Inside:
This shows only 1x sectional divide, i have in there 5x. Light can only travel in a straight line through air so this stops any light in/out.
Hot glue, bristol board and hook/loop strips.
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I’ve always kept the flaps sealed tight. Never once opened them. That said, @Gpaw nailed the filter intake. My only concern would be reduced airflow but wow — multiple tent upgrades happening tomorrow (filtered air! — and moving the fan and carbon filter outside the tent for more headroom).
You’ll find what works for your space. If you think it would cause a light leak issue — it probably will! Try to aim for a basic setup and then slowly dial things in without changing too much all at once. You’ll get there I’m sure!!
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well to be fair, the room my tent is in is rarely used, and dark at night… when I’ve been in the room with the lights on doing something it has not affected any flowering, guess because those velcro vents are down low under the canopy and not much light really gets in there, if worried just close up the side towards external light and use bottom and rear sides… I close em up just leaveing just enough to balance airflow and heat retention… it’s all about controlling that internal environment
Edit: just read all the other replies, Lots of good ideas mentioned here… It’s even opened my eyes for future possibilities if ever needed here…
Guess i should mention that I’m am not using a pull thru air filter requiring much cfm pull, just a fan on floor pointing straight up to circulate led heat down and around…
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From my experience most genetics can handle dark cycles that aren’t perfectly jet black. I’ve got 4 tents going and most have open flaps with small residual light coming through and never once had it hermed a plant or caused issues.
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Pretty sure AC Infinity makes baffles for tents. Kept em closed in the tents here.
$0.02
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Heh, I know its not a great option for alot, but I just keep my grow room, where tent is located dark during 12 off. Vents aside, my tent has some pin holes, and zipper leaks a bit. There’s a small closet in that room where I keep 2x2 veg tent so I can keep it lit 24.
When I break out my 4x8, which is better quality than one Im using now, Ill prob do something similar to @Gpaw and @Pigeonman. So I can work in there during 12 off if I want.
Heh, an advantage those who run autos have is they dont have to worry about that. But I prefer the control of photos, so…
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This is almost exactly what I have done, to a T.
Except I have a 6" booster fan inline, pulling/blowing in. 
I like this idea too!
My passive vents have always remained closed, for basically the same concerns as the OP(plus pollen containment).
Now this, I think that I understand.
I’m curious. You got some pics?
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@This1guy if you have pinholes you can use silver ducting tape to patch them. My POS cost me nothing used 2x4 was not a pos after some tape and cadle wax on the zipper.
Go in your tent with the room lights off and zip youeself insode. Apply tape until it’s dark. 
Alternitavly i also got a buncb of green xmas lights 75% off last jan. Thwy are strung in my geow area so when its full flower in all tents i dont turn on human lights and do my thing under the green glow.
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Thanks, will do with silver tape. How did you wax zipper? Just use a dark wax, and rub it on?
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I use white which comes out clear. Just go up and down both sides of the zipper with the candle or bees wax so you see some scraped up in the zips. Now open and close the zipper repeatedly and the friction will get the wax to travel in and around the moving parts lubricating everything so nothing gets stuck.
Now don’t got ape shit so it’s “waxy” but make sure you are doing damage to the source of wax (candle, bees, etc).
I usually need to reapply 1x a year if it’s very used tent.
This is a trick I learned from my Dad who when we were ice-fishing when I was a kid emphasized that maintaining a zipper can often make the difference between a safe or frozen pecker.
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Thanks. Def gonna remember that for other zippers too, coat, sleeping bag, whatever.
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You guys all have really great ideas and have given me a lot to think over. Thank you all for contributing.
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https://www.etsy.com/listing/1662713670/grow-tent-light-blocking-intake-filter
I keep meaning to try these if they’re ever in stock for my tent.
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