What fan size in sealed two room setup for circulating air between rooms?

Discussion in 'Grow Room Design & Setup' started by Sam&Max, Dec 5, 2017.


    Sam&Max Active Member


    I will build a room for flowering and a room for mothers. The rooms are side by side and are sealed.

    I need to circulate the air between the rooms for the CO2 and for scrubbing the air with a charcoal filter.

    Both rooms together have the size: 16.7 x 12.2 x 8.5 feet (1731 cubicfeet) (5.10m x 3.70m x 2.6m).

    Mothers room is between one third to half the the size of the flowering room.

    Can somebody please tell me if I need two fans between the rooms, one pulling air in the flowering and one pulling air in the mother room?

    Which size need the fans to be, considering that there will also be put a charcoal filter on one of them?

    I really don't want to oversize my fans, but I also need the operation to work properly and need the CO2 and heat distributed properly between the two rooms.

    justugh Well-Known Member

    this is really simple .......yes u need air flow between the rooms
    as for how much it all depends on u what lights are u using....... the mother room would be less then grow room but more then a dry room so if u have the ac/heating for all the area in one room u want higher cfm moving between the rooms but if u have split the system u only need enough to move the co2 and oxygen around

    as for carbon filters they are to clean the smell out of the air before u dump it ......u only need them if u think u are going to want smell control in the area or u need them to clean the air out of pollen/dust/mold spores

    so what is your heating cooling like and what is the sources of your lighting (HIDS put out alot more heat then LED/Cobs)
    Sam&Max likes this.

    Sam&Max Active Member

    Hi thanks for your answer!

    Now in winter the temperatres in the room are just above freezing point. So my plan is not to need any cooling now. Some tests before showed up results that it probably will work. In summer I will install a mini split in one of the rooms.

    For now I need to have the heat, the CO2 and the oxygen distributed between the rooms properly. I guess it would be nice to have an evenly distribution of the air between the rooms which is also not too slow.

    I will use the charcoal filter for keeping the air inside clean and odourless.

    I will run probably four HID Double ended fixtures at something like 825 Watt.

    justugh Well-Known Member

    ok u will have several issuses in the winter time
    1 the media touching cold floor ( this is ok with a hydro system a soil system u want the roots 55 atleast other wise it stunts)
    2 4 HIDs if they are open reflector u are not going to have enough heat for the rooms with out add ons
    3 hids if u leave the open reflector in spring and summer u are going to be fighting to controll the temp

    ideally u want to get the mini split now u can use a heating cooling one ( we got a 24k btu unit for 1100)........if u get a over sized system u can get 2 header units and have each room controlled on heat/coolness

    as for the rest super simple .......co2 is a heavy gas and oxygen a ligher one (so the area that has the Co2 gen in it needs to have a sucktion point low to the grow feeding over to the other room (i say have it eject out High so cooling and heating from other room has more effect) .....repeat this on the other room and u have made Air flow for Co2

    now u need to rem that the plants only want Co2 when the lights are on ......when they are off they like Oxygen .......so at some point u need to cut off your supply of co2 to allow the oxygen to build up for night time then in the moring u want to eject the Co2 that has built up over the night (it is a waste form of Co2 to the plants can not use ) zypher the air out get new oxygen co2 into the room and start the day running

    but a simple 4 inch booster fan of 90 to 100 cfms will do u ......just get 2 one that sucks and dumps into other room one that sucks and dumps into other keeping the balance of heat cool and co2

    as for carbons do not spend the money .......unless u run Ozone in the room that plants grow in u are not going to control the smell of the air (and ozone is bad for Co2 lvls ) ...........u can build a filter box out of carborad attach the fan to the back and put on a lvl 10 (or lvl 7) filter and that will clean the air for u as it moves around ..........lvl 10 is hospital grade
    Sam&Max likes this.

    Sam&Max Active Member

    so you mean pull the air from the ground and give it out on the ceiling of the other room? With an 90 to 100cfms fan. Same thing for the other room? If I pull the air from the ground, will the heat also distribute? I heard heat collects in the upper part of the room...

    I am still deciding which HID fixture I will take. I plan to switch the reflector hoods in summer for air vented ones.

    I am growing on four ebb and flow tables, which don't sit on the ground.

    Maybe I will light at night, so it doesn't get too cold. The place is really good insulated. And then I insulate the flowerroom and mother room once more. So I hope I can keep the extra heating minimal. Mini split now is not really an option. But maybe..... I will think about it. I might put an electric heater inside, so the temps don't get critical.

    Please tell me why carbons don't kill the smell? I really thought they will do...What kind of filter do you mean lvl 10, I don't understand?

    Is there really the need for sending out the waste form of CO2 outside? Do you know where to find infos about that waste form of CO2? I never heard about it before...

    Thank you very much for your advices.

    justugh Well-Known Member

    np glad to help

    yes on the air flow .......this is more for dumping the CO2 between the rooms keeping the mix of it flowing around so it all does not settle to the ground ( this is the cheap halo effect)....the summer times it will help cool the areas keeping them near the same temp (as for heating it will lvl out the area so once they reach temp they do not need to keep getting there it holds for longer)

    ok then u need to know the higher up the plants are the more CO2 needed to fill the area bud lvl .....this means more to get it up to lvl and u need to watch yourself in there (if ever feel faint or out of breath leave area for open air fast) 1500ppm at bud lvl will be 2000 near ground and u will be mixing with what oxygen is in there

    lights on at night is what alot of us do just for that reason and the power bill is less as u are not using all the energy u need during peak billing hours .......the units like a base borad heaters work if u have too i go the little heater fan units that way it warms up and keeps a good air flow under the plants

    ok the reason a carbon filter will not work to control the smell in your area is the plants themselves are making the smell .......unless u are willing to use a ozone gen to attach and then burst killing the smell as it is made no way to control as it is growing in a area........carbon filters due take the smell out but that is when u are dumping the air outside the grow room (your in a sealed system to let the Co2 build up beyond nature amount to push plants) the air only gets exchanged in your system when u enter or leave the area/leave door open.......cleaning that air of the smell will not do anything u will always smell it in that area

    when u go to a store and look at filters for houses and all that they have a scale on it 1-10 ..........this tells u how much the filter traps what kinds of things and partials/ mold spores/ virus/ pollen........a lvl 10 will trap everything including smoke partials it is hospital grade

    i would on the waste Co2 .......this is how it was explained to me when i was thinking about a 100% self contained area and not adding Co2 from outside source
    when the plants are on they use the Co2 that animals make from breathing they take that and convert it into Oxygen we need now when the lights go out on the plants they need the Oxygen that was made and they release a Co2 a form that they can not reabsorb and use it is ment to move down the chain and get mixed with what we made and the ocean system absorbs it for it life in the water and they make oxygen ........the room needs to be aired out even if it is just opening the door to enter and holding for 30 secs .......how it was explained to me

    Sam&Max Active Member

    I plan to have some fans on the ground to send the air upwards.

    I looked at the link with the filters. It is some fiberglass filters. I don't know. So far I had good experience with carbon filters. Also I tried to find information which says that carbon filters doesn't work in a sealed setting and I couldn't find that information.

    Also same with the waste form CO2. Do you have a link with information to that two subjects?


    justugh Well-Known Member

    the smell part is simple ........because the plants are growing in there the smell from the plants can not be cleaned out with out killing the plants ( the smell comes from the oils the plant makes and volatilizing to the air makes the smell) ....a carbon filter will not fix it what u are talking about is called Air polishing it only works in areas that the plants are not in

    carbon filters are a waste of money in a sealed room( it is just a big giant dust filter) .....a simple lvl 10 filter will do the job as best as u are going to get it
    the only other way i think to explain it is ok the smell is the color red and the air is water ......u can filter out the red but as long as the source of the red is in the water the water will never be clear (just waste of a filter)

    as for the waste Co2 ......like i said that is how it was explained to me from a grower i trusted .......i fallowed his advice and made my system a exchange enriched with Co2 ( a 200 cfm in a 11x12x7 room) i feed into the room using a filter box and in the box poked a hole for a Co2 tank to release 0.20 cubic feet a hour to raise my room to 1000-1200 with a natural ppm of 600ppm
    psychadelibud likes this.

    psychadelibud Well-Known Member

    Hey man you seem to know your shit pretty well. I need some serious help myself and would love for you to head back to the design and setup main page and click check out my post.

    I am having trouble figuring out my venting and entire environmnt for that matter. I need this room functioning and ready to grow by beginning of this coming week.

    I would explain the situation here but you can read through the thread so you will know my situation a bit better. Thank you in advance if you don't mind!

    Sam&Max Active Member

    I understand it like that:

    Activated carbon works by a phenomenon called “Adsorption”, which is where the odor compound is trapped inside the activated carbon and retained, but the material doing the adsorption does not change size. ADsorption differs from ABsorption, which also removes things, but is characterized by swelling (see Figure XX). Both adsorption and absorption media have fixed capacities, meaning they hold just so much, since they are storing the material removed from the air, not destroying it. Frankly, it is easier to tell what is going on with ABsorption, since the size increases equal the amount of material removed. In ADsorption, there is a weight gain, but it is hard to measure and we need to use other means to gauge the remaining life of a carbon filter.

    Activated carbon removes odors by offering the odor-causing compound a more attractive place to reside than circulating in the air. This more attractive place is a thermodynamic definition, not a matter of choice on the part of the compound. The adsorbed state, which is when the odor compound leaves the air and gets retained inside the activated carbon, is called a “lower energy state”, which is like the molecule falling into a hole and not being able to get out. Brand new activated carbon has lots of unoccupied holes, and virtually every compound that passes through falls in a hole and is retained.

    From the following source: http://www.phatfilter.com/understanding-air-purification-activated-carbon-filters

    I don't see the a principal difference keeping the scrubbed air insite to sending the air outside concerning odor wise....

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