Sealed grow room with constant circulation, and co2

Discussion in 'Do It Yourself' started by applepoop1984, May 27, 2013.


    applepoop1984 Well-Known Member

    hello i would like to start by saying a common problem with rooms running constant exhaust is a lower concentration of co2, not as low as a room with no exhaust but not as good as a sealed room with co2. he problem some people have with sealed rooms with co2 is excessive temperatures. i believe plants can utilize up to 7500-10000 footcandles at 90-85 farenheit co2 with a ppm less than 1200 at a relative humidity below 50% but above 40%. with a sealed grow room all of these factors are much harder to control, while maintaining a consistent level of co2

    i think i have a solution and it is a sealed grow room with recirculating exhaust.

    1st make sure to seal up your grow room completely. a good way is with duct tape. i envision this in a 3x3x6 ft grow box with three walls and the front being a sheet of pandafilm/mylar/reflectix etc. on one side will be the intake fan or pusher fan, not the most efficient design as far as air movement but necessary to recirculate exhausted co2 rich air. this fan will be on the lowest part of the pusher fan side as this will provide colder air by the means of the exhaust duct acting as a heat sink.

    cut a hole in the pusher fan side and install the fan and seal around with duct tapemaking sure there are no leaks.

    next we install the puller fan side. install puller fan on the side that is opposite the pusher fan and at the highest pointof the box, even the ceiling of the box is acceptable and preferred as this will be the highest point of the box allowing the most heat to be able to escape and be cooled. secure the puller fan on ceiling or wall opposite the pusher fan and make sure it wont fall duct tape is good for sealing but may need other support such as hooks etc.

    now we install the recirculation duct. install ducting the exact diameter of both fans so that the puller fan connects to the pusher fan so you have one fan pushing air into the room and another pulling that same air out of the room in a constant loop.i find its best to run the exhaust duct from the puller fan, behind the box and around to the pusher fan.

    now you are done. it is important to be able to control at least one of the fans speeds for most control how ever if you can only use one fan controller make it for the pusher fan as the puller fan will always be limited by the rpms of the pusher. it is even possible to use one fan but make sure it is the puller fan up to to increase upward air movement maximizing co2 uptake

    no you have much more control as opposed to running a fan timer in your grow room plus these added benefits:

    1 less wasted co2
    2 more consistent level of co2
    3 ability to control humidity more easily
    4 easier temp control
    5 less risk of outside pests entering
    6 increased air movement in the grow room, co2 is very dense and tends to pool on the bottom so upward air movement and negative pressure are helpful
    7 reduced odor

    i hope someone found this useful i will be implementing it soon

    a side note this setup is intended for co2 only, without co2 enrichment the plants would use up available co2 as well as recirculate hotter air since it is a sealed system

    i am still working on how the fan speeds will affect temp humidity etc any insight would be appreciated

    applepoop1984 Well-Known Member

    any comments criticisms suggestions thoughts musings critiques would be appreciated.

    iv been thinking that this would be the perfect setup except for the humidity build up, i do not want to use a dehumidifier if i dont have to, like wise for an ac,

    some of my thoughts at remedying an excess of heat and humidity would be:

    a coffee can or similar cylinder in between the pusher and puller fan , on the outside of the grow box of course, that the ducting would both exhaust and pull air from( from each respective fan,) and the coffee can or other cylinder would have cut outs on each flat surface to be flush with ducting, and there would be screens on the inside between you could fill silica gel( not really gel) or some other form of desiccant. once the silica gel is no longer useful ie you notice the humidity rising to an undesirable level, simply empty the coffee can and replace with a separate desiccant while drying out the moisten desiccant. repeat.

    silica gel is very common and cheap it is found just about everywhere, beef jerky, vitamin bottles, even sometimes new shoes. alternately you can buy some for silica gel, around 900 grams for 25$ shipped on amazon, or you could use an alternate desiccant such as activated charcoal, which may be cheaper at around 4$ a lb

    to remedy the heat if the gail force winds from both fans fail to yield any results would be, one more exhaust only pulling air from the light if you have a cooltube setup, and having it so it vents out the top of the box and having at at a slower fan speed than the exhaust fan that recirculates.

    another option for heat would be liquid cooled lights, which would eliminate the need for my recirculating system if it were not for the advantage of having co2 being pushed and pulled in such a manner by the 2 fans that the co2 is being pulled up from the negative pressure to be best utilized by the fan leaves

    another option for heat would be lengthening the re circulation duct so to increase the surface area of the duct which would act more like a heat sink absorbing heat from the hot air passing through it. keeping the duct on the floor where it is coldest would also help. this will also increase the volume of the grow room meaning slightly more co2 needing to be used but it is not significant .

    bare in mind you only have to have your temps below 90 degrees farenheit so as long as your between 85-90 with 1200 ppm co2 or less you will have no problems.

    one more very important thing i forgot to mention, ethylene build up from co2 recirculation as well as sealed grow rooms can be problematic to yields. always vent the room for at least 10 minutes a day to remove ethylene buildup, preferably twice a day. and temps over 90 degrees are not beneficial as they inhibit rubisco.

    to vent simply remove the ducting from the puller fan for 10 minutes .

    applepoop1984 Well-Known Member

    poke poke poke

    applepoop1984 Well-Known Member

    to combat heat im somewhat stumped. my main thoughts are using the ducting as a heat sink but i am not sure abotu how to do this to keep levels below 90 degrees. im thinkin keeping it on the floor should lower temps 1 degree,another would be , and i think this may be the best idea, is to have a small fan mounted on the top of the box pulling both heat and ethylene out. having this fan have less cfm than the puller fan mounted on the top of the box would be best so that it wont pull dense co2 particles out of the room while pulling rising heat out and possibly ethylene

    density of co2= 1.98 kg/m cubed
    density of ethylene= 1.18 kg/ m cubed
    density of air= 1.225 kg/m cubed

    so ethylene, being lighter than air, should be getting pulled out readily , and co2, if getting pulled at all should hit the puller fan below the ethylene and heat extractor fan since it is much denser.

    now the only problem left is positioning of the heat and ethylene extracting fan, and the recirculating co2 puller fan.

    if placed on the ceiling of the box it should leave co2 to recirculate, especially if it has a lower cfm than the recirculating fan.

    next would be to mount the fan just above the point where the top of the canopy is . i think this solves all problems
    so basically here is a short synopsis:

    1 seal box
    2 install pusher fan at bottom of the box on one of the 3 walls
    3 install puller fan on wall opposite of the pusher fan, just inches above wear you estimate the top of your canopy will be
    4 install puller fan with lower cfm than other fans on ceiling of box, opposite the wall of the recirculating puller fan
    5 connect ducting to puller fan with dehumidifying cylinder in the middle
    6 connect dehumdifying cylinder to pusher fan with ducting
    7 cut baseball sized hole on same wall as pusher fan, at least 6 inches above top of canopy, basically close to the ethylene/ heat exhaust fan a picture is now included for clarity

    picture!!!! sort of...

    co2 room.jpg
    kulakush likes this.

    Red1966 Well-Known Member

    This set up won't provide much cooling or dehumidification, if any at all. You will be just pushing hot moist air back into the tent. It will do nothing for odor control at all.
    kulakush likes this.

    Red1966 Well-Known Member

    If co2 settled out of the air as readily as you think, the first thousand feet of air outside would be all co2 and no life would exist below that level. I suppose if you made your cooling loop 200-300 feet long, it would work as a heat sink, but only if routed through a cooler area. Unless you live in a giant air conditioned warehouse, I don't see that working. All the other fans you mention will exhaust your co2. Activated carbon doesn't dry the air. Silica gell would get used up at an alarming rate. 20 plants give off 2-5 gallons a day of water. 2 gallons = 16 lbs. Hove much water can a pound of silica gell absorb?
    Kevin the Great likes this.

    applepoop1984 Well-Known Member

    there is an exhaust fan mounted on the cieling, i have a co2 monitor as well as humididty and temp monitor in the box. the cieling fan is 5 feet above the floor of the grow box. this is to keep temps in the 85-90 range. 1 plant will be used in this setup. i will record my results as well as run some test runs. it should work, the bottom will be sealed and only the top 6 inches will be pullign air out from a from the ceiling vent fan. i will cut a small hole in the top near the vent fan so to suck heat away from the light and vent ethylene

    this will work because:

    co2 is very dense, almost twice as dense as air 1.58 kg/m3
    hot air is very thin 1.16 kg/m3 @ 85farenheit
    ethylene is extremely thin 1.18/m3 @ 59 farenheit

    so hot air will vent, ethylene will vent extremely well, and co2 will pool at the bottom and be recirculated. i anticipate humidity to be no more than 60% with only 1 plant. re read my follow up posts in this thread and look at the picture to get an idea of what im attempting

    silica gel can hold 40% of its weight as moisture. 1 pound of water will not =100% relative humidity and yes carbon is in fact a desiccant. dessicant will be replaced daily and heated and at 5$ per 900 grams i could make it as much as 4 pounds without spending more than 12 $

    bass1014 Well-Known Member

    this is in the wrong forum it should be in design and set up not diy.. your the pot calling the kettle black aren't you?


    applepoop1984 Well-Known Member

    it is diy i assume grow room design is for questions about grow room design this is a diy how to make a sealed recirculating co2 grow room step by step with a picture i might add co2 room.jpg

    point being this is a diy tutorial it most certainly belongs here. we have posts about making your own organic soil from tropical rainforests from hawaii to indonesia which doesnt belong anywhere on this entire forum lol. you are 100% wrong on this one iv included step by step instructions on how to construct this setup. sorry to sink you're dinghy

    DabberKing Active Member

    im thinking about trying to out your set up appleloop! how did things turn out?!
    Kevin the Great

    Kevin the Great Well-Known Member

    Why not just throw in blocks of dry ice? It would help cool the room while evaporating into CO2. That sounds like far less work than changing your carbon daily.

    kulakush Member

    To ventilate or Not to ventilate?

    Many argue that there is no need to ventilate a sealed grow room environment because you can simply supplement CO2 and scrub the air with a carbon filter. They say it's a waste of money to let excess CO2 escape and that there is no benefit in doing this. Then I ask them how many sealed grow room environments have they've built and it's usually only a few.

    The proven benefit of a sealed grow environment is that you can control and really dial in the elements of the environment to achieve better results than a traditional open air exchange system. The general concensus is that you can truly achieve better quality and maximize weight with a sealed grow room setup. But are you truly maximizing your results?

    While many claim to achieve good or great results with a completely sealed room with no air exchange, and also never experience any issues with plants my experience has shown me otherwise.

    I've setup many sealed rooms the exact same ways where I have achieved great results and other times I've gotten different results using the same exact setup in a different place. This has boggled my mind for years of why this may be happening. Some places I pulled my best grows and yields and others have given me moderately average results to my grow standards. I don't know the reason yet why this happens sometimes but I've come to the conclusion that when you take away what's worked in nature for millions of years and then attempt to fabricate it by adding all the known needed elements to properly grow cannabis correctly you would expect to get the same results but time has shown me that this isn't the quite case. I've seen unexplained plant problems, small nugs, plants getting freakish leaf wilt, plants acting weird for no reason etc with sealed grow rooms that all had one thing in common and there was no air exchange. Wether it's bad gases in the environment, like excess ethylene or drowning your root zone with too much CO2 etc who knows. Let all those arguments continue. What I do know is that ever since I started running hybrid type systems all the freak problems went away and I am achieving the results of what one would consider a master grower.

    There is a way of getting better results by running a hybrid of both systems. Taking what already works in nature and combining it with what man has discovered with CO2 enrichment and environment control to form a hybrid system that helps keep the known and unknown important elements of the environment at balance is what I found to be the key for the perfect grow room.

    A hybrid room that is sealed With CO2 enrichment and at the same time ventilated with a continous exhaust fan running at a much slower rate usimg a dimmer so I don't suck out all the CO2 in minutes so that I can still maintain the proper levels of all the necessary known and unknown elements in the environment of nature was the key to having all these freak issues go away. After doing this I've never seen these problems crop up again. Even though my CO2 expense goes up a bit my yields have been the best ever. The buds just simply get bigger. Hitting over 3+ pounds a light with gavita fixtures. When I didn't vent my sealed room I would get 2.3-2.5 a light. I learned this from a very experienced grower in the San Fernando valley. He is the guy who created the sfv og strain. This is how he does his sealed rooms and hits 3.5 pounds a light on a consistent basis. Every grower out here in the SFV that hits over 3 a light runs theirsealed rooms like this. The first picture is my top buds from my og kush strain using the hybrid system, the second picture is a top bud of the same og kush strain under a traditional sealed grow room with no air exchange. I still don't know the science of why this occurs but what I do know is my results from my past experiences growing og kush and the secretes of the best growers of the SFV which first put og kush strain on the map and made it famousto the rest of the world.

    Attached Files:

    kingromano likes this.

    kulakush Member

    I use a 2 way AC split system that has intake to recirculate the air in the room and cool it down and dehumidify it at the same time. The way I do my room is that I seal it and run a continuous intake and exhaust system that exchanges the air in the room very slowly. I use a fan dimmer to accomplish this. But what about those days when the outside air is hot and humid? The solution to this is to run a duct from your intake point and place the fresh air intake duct next to your split AC system intake so that the hot or humid air coming from a day with bad weather can be treated through the AC system before hitting the canopy.

    grassy007 Well-Known Member

    If you have a source of fresh air (window) for a sealed tent, I don't see how a plant would not be getting an adequate amount of Co2, regardless of intake or exhaust methods.

    Flowki Well-Known Member

    OP kulak way sounds perfect. With both in/out take at top the cooler denser air should not get sucked out much at all. Only issue is if you can control temps while pulling so slow. Given that cob/led push heat up they would serve this idea even more as you'd easier maintain a cushion of cooler air low down to inject co2 into. If you really wanted to get smart about it maybe you could put a semi sealed container filled with water on the floor. If you hook an air pump up to it and the surrounding air is filled with c02 it will, I suppose charge the water and act as a co2 battery. With only a small exit hole to gass off out, it should keep humidity release to a minimum while reducing the amount of co2 lost to out take. If it should work in such a way.

    Very interesting method none the less @kulakush good read. How do you control the circulating air flow to refresh leaves but not draft it up into out take?.
    Last edited: Jan 22, 2018

    kingromano Member

    ise bottled co2 used or is it a burner ?

    is that necessary to vent with bottle co2 ? and when would you do it by your experience ? beginning of night ?

    Ednun Member

    Looking forward to results. I was thinking of bleeding a welding C02 tank into the canopy to test.

    nonamedman420 Well-Known Member

    get a chiller, or repurpose an old a/c as a chiller. get a heater core from an autoparts store, some hose, and a water pump. make a diy icebox, and you can attach a fan to it using 2 rectangular ducti adapters (one that is just longer and wider than your heater core) you can use pipe insulation around the heater core to fill the gap between it and the duct adapter. i've done his personally, it works. put it in the room and it will regulate the temps and humidity, set the water temp to be 10 degrees F lower than your wanted room temp. set the fan to a thermostat or a fan controller and dial it in. make sure the fan pushes through the diy icebox, and the fan is higher than it also so the water from the dehumidification process can drip into a bucket. this will be some of the cleanest water you can use to mix nutes with too. google diy icebox, if i find my setup in storage i'l post some pics and links to the parts.

    edit: i used this setup for a fresca sol water cooled light, but converted to led so it's sitting around somewhere, as is my 1/4 ton chiller. the money we waste in the drive to make the best setups possible. we then wise up and think how can i do this easiest, and most importantly, cheapest.

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