+Earth.Hawk Thanks EarthHawk!

Thanks amigo.

andrea a Thanks for the smile Andrea-have a great weekend. :)

Aaron .

+Ruben Chavez yes, input should shift around 70% of your output / extraction

Hi Kevin. Thanks for your question. It's very interesting and there's lots to consider. First, some numbers. If you're planning to use a carbon filter then you should add 20 to 25% to your MINIMUM CFMs bringing us up to around 85. I will assume that you are running open (non-AC) hoods and you are growing light-loving, flowering plants through to maturity and harvest in the same small area. Now, given that it is so compact and you will have mature plants in there (which probably prefer a lower RH of 40 - 45% while transpiring heavily!) I would personally spec your fan a little larger just to give yourself some wiggle room. A 6" Hyper Fan moves 315 CFM and you might think that's overkill - but it's not, especially as you can dial it down to 35% sped with the included speed controller and remember you have to reduce that number by at least 20 - 25 % due to pressure drop (filter, ducting, etc). The hyper fan uses even fewer watts when dialed down. I don't know where you live, but if it gets hot and / or humid you'll be glad you have some "throttle" power left with a 6". A passive intake will be fine - make the hole at least 4" in diameter and cover with a bug mesh. Good luck and keep in touch. Everest.

+Everest Fernandez (Just4Growers) Ok thanks! and I'm In the United States over in Oregon. getting ready for winter over here! lol. anyways with a 2 x 2 window and 1 x 2 opening in the window to use do you think it would matter if the extraction and the passive intake were to share that space being that close together if only pushing for that small of a space?

+Kevin Farmer Your intake and extraction points should ideally be at diametrically opposite points in your grow room. Extraction at the top, intake at the bottom, on opposing walls-that way your plants stand the most chance of benefiting from the fresh air rather than creating a sort of 'slip stream' that bypasses your plants in the case of intake and extraction points being located too close to one another.

Matt Holy Thanks so much Matt! I'm really glad that you are finding the videos useful. First and foremost I do my best to look out for beginners, as we were all there once. I live and breathe this stuff and always do my best to answer viewers' questions, particularly if they come from a subscriber-so, on that note, thanks again. ;-)

Matt Holy I agree Matt In a way it is Art.

Rafael Rassi Hi Rafael. Thanks for your question. Your grow tent is 1.152 cubic meters. (.8 * .8 * 1.8). You need an extraction fan capable of exchanging the air in your grow tent at least once per minute. Fans are rated in cubic feet per minute (CFM) or cubic meters per hour (CMH), depending on where you live in the world. As you specific your tent dimensions in metric, I'll go with CMH. 1.152 * 60 = 69.12 CMH. However, if you are using a carbon filter then I recommending adding 20% to this figure. 69.12 * 1.2 = 82.94 CMH. (48.82 CFM) A 100mm or 4" diameter extraction fan connected to a fan speed controller (e.g. Zephyr 1 by Titan Controls) would be a good choice for this size grow tent. I know that was a lot of numbers! Let me know if you have any questions. Always glad to help. Peace and happy growing, Everest.

Thanks a MIL man, i was almost buying this one www.airfan.com.br/loja/index.php?route=product/product&path=51&product_id=205 because i thought it would do the job... THANKS again

Rafael Rassi My pleasure! That fan you link to is 6 inches (150mm) but the CMHs are low! A 6" Hyperfan with its built-in speed controller would give you more than enough extraction power, but it depends what's available to you locally.

I ended up buying www.growplant.com.br/exaustor-axial-in-line.html Will it work fine on my tent? With the carbon filter?

Rafael Rassi The specs look fine to me Rafael. Next step is to purchase a 4" carbon filter. For that sized grow tent I would just rely on passive air intake (no need for a fan to blow air into the tent.)

yes with a fan speed controller, bigger fans are quieter too on lower speeds.

SUKHDEOSINGH RAJPUROHIT Hey Sukhdeosingh. You ask a very interesting question, because your ceiling height is so unusually high. Higher ceilings give you a larger "buffer" of air and do not necessitate larger fans as some formulas might suggest. If your room is full of plants (that is, your active growing area is 45 x 30 ft) then I would suggest using fans that move 12,000 - 16,000 CFMs in total and attaching them to speed controllers. Move towards the upper limit if you are using carbon filters which lower the CFMs by around 20%. I believe it is preferable to over-spec, use speed controllers and be ready for spikes in ambient temperature than having your fans on maximum all the time and not being prepared for external environmental extremes. In practical terms, you would need one 10" Hyper Fan (for example) for each of those 1,000 CFMs you want to move, so you're looking at 12 - 16 fans. Alternatively, you could go for larger 16" fans that shift more than two and a half times the CFMs of the 10" fans. Larger fans are available but it might be beneficial to extract from multiple points with such a large growing area.

cfm x 60 divided by volume of room - for cannabis you need about 15 ach

+John Smith Hi John, thanks for your question. So your tent is just under 48 cubic feet. Your fan is rated at 412 CFMs. Attach a carbon filter and that will reduce output by 20%, so now we're at 330 CFMs, but ducting arrangements could bring this down further to around 275 CFMs. We're still way over your required minimum of 48 cubic feet per minute but if you are living in an area of high humidity then it might be a good idea to have the extra power-especially if you already have a fan speed speed controller. I'm not familiar with the Gail Force brand and its compatibility so I'd have to get back to you on that one. The slower air moves across the carbon bed inside a carbon filter, the more contact time the air has with the activated carbon, and the better it will work. Your chosen carbon filter (iPower GLFILT6M Air Carbon Filter (6 inch x 16 size)) is rated to filter air moving at 400 CFMs or less so you should be okay. The filter should be positioned as high up in the tent as possible, ideally vented out through the roof port. If you have mesh inputs at either side of the tent then the middle is the optimum position. You could use some clip-on wall oscillating fans to help circulate the air but be sure to choose a premium brand that's rated for constant use as the cheap ones tend to burn out and can present a fire risk. I hope I answered all or most of your questions-let me know if you have any more. Peace out, Everest.

+Everest Fernandez (Just4Growers) yes, you've answered, with great info too. -- The slower air speed thru the carbon info, and its placement, is very helpful :) -- will the slower air speed thru the carbon extend the carbons life, or use it up faster? ...! ... :-o ... :) ... I'm glad I'll have so much 'wiggle-room' with the CFMs because I recently found out the built-in micro-mesh filter on the tent will leak light, so I'll need to make an upside-down 'U-bend' with ducting, thru one of the tents lower ports as an air input, to block any light leak...I hope...will that work?. -- are there any micro-mesh 6 inch duct intake filters for sale to put on the bottom of that U-bend?

+John Smith Hi John. The slower airspeed will not extend the carbon's life-that's determined largely by the amount of surface area on the activated carbon's micropores. For your 6-inch duct intake check out something like Black Ops' bug screens ( goo.gl/3WlOSa ) or a Phresh Intake filter ( goo.gl/MZgYCd ) - the latter wouldn't require a U-bend.

Hi Phillip. Thanks for your question. For intake, use a specialized "intake filter" - e.g. Phresh or Hepa - they just remove particulates. Carbon filters do this, but also remove odors, and are generally used as air scrubbers or as part of an extraction system.

+Everest Fernandez (Just4Growers) okay I thought Presh was a type of carbon filter for intake. That's what I was confused about. Thanks for the help. Your videos are the best.

+Phillip Tussey Any time! Phresh make both intake and extraction filters.

Nice space Greggory! You can get more powerful fans than 750 CFMs but it's no a bad idea to spread your air exchange requirements over multiple fans for a space like that.

Everest Fernandez Thanks for the reply! With multiple fans for proper air exchange would I need more exhaust?

+Greggory Brandt Normally indoor growers spec their exhaust fans slightly higher than their inputs (be sure to allow for any pressure drop due to carbon filters on your extraction side too, usually around 20 - 25%). By extracting more air than you input you create a 'negative pressure' inside your grow room which makes it easier to control your grow room's environment and any garden odors as air is being pulled into your garden through any leaks, rather than being pushed out. All that said, I know of a grower in Holland who swears by positive pressure-he tells me that it increases the amount of effective CO2 in his garden. I guess 20% more pressure = 20% more CO2, and-as it's such a crucial input and often the bottleneck of indoor gardens reaching maturity-he may have an interesting point! I'll be looking into this next year.

Hi John, thanks for your question-it's a really good one. Firstly, to answer you directly: twenty years ago, if you were to attend an "indoor gardening" trade show (as they were marketed back then) you would hear fan manufacturers and professional growers recommend one air exchange every two to three minutes. Then, as lighting became more powerful, it gradually came down to one exchange per minute-and, due to the simplicity, this recommendation kind of stuck. Of course, it was born out in the real world too. Now, THIS VIDEO is eight years old and, during that time, we've seen LEDs take the market by storm. Now the air exchange recommendations are even higher. TWO exchanges per minute and more! Of course, these are massive generalisations that don't take into account the ambient environment / climate. But it's ALWAYS a good idea to over-spec your fan (if you're trying to decide between a 6" and an 8" EC fan for example, always go for the 8" - not because I'm taking a commission on all brands' fan sales - but because you can run it slowly, without additional whirring noise, and you have the extra bandwidth for moving a lot of air if you need to, on hot days / nights, etc, and it will always run more quietly than a smaller fan moving the same amount of air through narrower ducting. Seeing how long this reply is already getting, I think I need to completely revise and update my grow room ventilation series for LEDs - as they have completely changed the goal posts. Before, the main bogeyman was HEAT and that was the main reason we vented-now, it's more about humidity and CO2 replenishment - as LED rooms like to be run a little warmer to make up for the lack of IR in the LED grow light spectrum. So much to discuss! You can always reach out to me personally at just4growers@gmail.com or we can continue the discussion right here if you prefer. Interested to hear your thoughts on this.

Mike P Absolutely! It’s been on my list for as long as I’ve been making videos! I’ll get it done this year :)

I'm actually good friends with the owner of my local hydro store so I go visit him pretty often!

Once you buy the setup, it's really cheap to maintain. Also, $400 for a setup that will allow you to grow over a pound of weed per cycle will pay for itself several times over after the first grow. Also, when you live out in the country you'll constantly have other people scouting out and stealing any crops they find. You won't harvest unless you plant them in the middle of a cornfield (which makes for shit weed), or deep in a forest.

you didnt think very far there. Once you buy you dont have to buy again and maintaining it is even less. most your cost will be electric, seeds, soil, and nutrients depending how you do that. i spend 3k and got way more back so it ends up funding itself. So either you are not really interested in growing or your are lazy

+x2eXu50x Hey x2-thanks for your question. It's funny you should ask at this present time because I am in the process of creating some follow-up videos on this very topic, so please stay tuned (or rather, subscribe!) so you will be informed as soon as I upload them. Thanks! :)

Everest Fernandez Great will do! Thanks.

I released a video just this week.

+Robs Hi Robs-thanks for your question. I enjoy speaking with fellow growers from all over the world. (What is your first language?) Your best option is to bring air in from another room in your house as the temperature and humidity of this air will be more stable than the outside air.

Ok that's what I'm going to do. I was trying not to cut a hole on my house but rather be safe than sorry.my first language is Spanish ,and I have one more question I just bought a filter last night I accidentally let it outside It got wet it rain all night D

Do you think still good?

+Robs Ola Robs.Estará bien. Sólo tiene que dejar que se seque. (It will be fine, you just need to let it dry out.)

Que Bueno.me salve de comprar otro

Jammin Dave Lol! It's a cheeky set-up, for sure Dave, and I hope that I'm fully future-proofed for planned expansion and / or hot summer temperatures outdoors! Thanks for sharing my videos and I hope you subscribe to the channel for regular updates on my F15s :)

ja ja ja very funny. Good luck with your growing plans...later!

Still searching for the right variety to grow indoors

Taylor Working on it :)

Sooooo I'm in the process of converting from a small grow facility ( two rooms) to a larger grow facility two buildings 2400 sq ft + 8000 sq ft. It is intimidating to bootstrap this with a life worth of savings and design a commercial operation. Selfishly I hope you might do a video around design/scaling...

Hello there amigo. It's typically recommended to BLOW air through air-cooled reflectors in order to create a positive pressure inside of the attendant ventilating ducting system. This means that any small leaks in your air-cooled light ventilation system will need up blowing air out back into your room, whereas if you suck, you risk sucking unfiltered air into your ventilation system which could disperse terpenes into areas where they are not expected or welcome.

Hi Damien, in metric? You'd use CMH or cubic meters per hour. 180 CMH would be your minimum or 65 CFM. I'd recommend going bigger and using a fan speed controller. Always good to have some spare horsepower should you need it in the warmer months.

yes metric, Tnx

I like to draw my input air through an intake filter to keep things super clean and sterile in my grow room. An active intake fan works well in this situation.

@@Just4Growers For sure. filtering would be a good reason to not do passive. But so many of these are going into little closet set ups, and most people don't bother much with filtration on those. Although, if you have adequate stand alone filtration, such as the EN 1822 classified IQair health unit, then intake filtration doesn't have to be as stringent. If you have something as high quality as EN 1822 HEPA, then all you really need on the intake is a light MERV for bigger pests and low pressure drop.

stevecameron85 That’s great advice Steve, thank you.

yeah those ribs inside make for a ton of turbulence. I use the flex ducting only when solid is not an option. also stay away from 90 degree bends- they kill flow too!

No chance of taking air from an adjacent room? You could consider a sealed environment.

@@Just4Growers hi. No. I isolated the tent but its in a place with no room isolation. And cant take air from inside. I tried to open the top intake passiv. And there is isolation infront of the holes. It seems to do good. Only a few degrees up and down and the same with humidity. But dont know how is gonna react when its colder. Any info about sealed environment. Not many talking about it on the net.

@@user-jm5hg3qi4f Check out monster gardens. (youtube) lots of info on sealed rooms. Hope it helps you out. Good luck.

Yes - 24/7

@@Just4Growers Thanks

@@Just4Growers Just the light turn on and off, in a cycle?

Hector Luis Colon Rosado yes - keep the air moving and exchanging 24/7 and run your lights according to your plants’ preferred photoperiod.

Everest Fernandez thanks your videos are awesome

andrea a I am more than happy to provide you with any help you may need Andrea. It's my pleasure to do so!

+Hannible100 Yes, it's French - over 300 years old. Quirky to say the least.

If you have a room full of healthy transpiring plants they will quickly fill the room with humidity and deplete carbon dioxide levels during the day cycle. However, since this video was made, LED grow lights have become very popular and they change everything! Look out for an updated video soon...

@@Just4Growers 7-8 times an hour is plenty. I've never had problems at that frequency. The plants' respirations is simply not that fast to replace the air every minute. That's way too much and is wasteful as one would need much larger appliances to do that.

No one likes a mooch. And he doesn't grow cannabis kid.

+wacatz1 to suffocate plants you would need to deprive them of carbon dioxide and / or oxygen. Exchanging your room's air with fresh air is a cheap and effective way of avoiding this.