Setting up a CO2 grow room.

Howdy fellas and ladies

I'm about to embark on building a CO2 supplemented grow room. I know that this community has a wealth of wisdom and experience so it seemed like a pretty good idea to put up a post and give a run down of my plans for you guys to critique and offer advice on and hopefully help me out getting this thing up and running.

This is my plan so far.

The room is a fully sealed and insulated 20 X 15 X 9 foot high shed. For environment control I will run a 7kw split system, 2 or 3 large dehumidifiers and a CO2 bottle set up with a controller to target a ppm of about 1200 - 1500. I'll also have a couple of large fans moving air around the room to keep the levels homogenous throughout the whole space.

Inside the shed will be 2 tents. One for veg and one for flower. Veg tent is 5x5x8 and flower tent is 5x10x8. Each tent will have active airflow in and out + multiple circulation fans. Running coco DTW in 7 gal fabrics. Lighting powered by 3 spider farmer SE1000W's, 1 for veg tent 2 for flower tent. Plants rotate from to veg to flower everything run from clone, veg/clone runs for the same 8-10 weeks as flower cycle, rinse and repeat.

Nute waste collection + dehumidifier tanks will all self empty into a 50 gallon dump tank which will then self empty onto the gardens in the yard.

My biggest question is assuming that my vpd and CO2 levels are constantly in check do I need to have any air exchange to outside the shed at all?

To me exchanging air means an increase is cost. Outside temps are very hot in the summer and very cold in the winter so my AC will be working a lot harder to maintain temps. If anyone has run this type of setup before I'd be happy to hear your opinion.

Also wondering what kind of yield increases should I expect. I'm currently getting about 1.5 ounces per square. How much would that go up in a boosted C02 room?

I've probably skipped on a few details so any and all questions are more than welcome.

KK

Are you going to be running the mini split inside units inside the tents? If so all you need is a dehuey inside the tent and the co2 line and controller in each tent. What will the lighting source not that it would matter with a ac in the tent

Onextremebuzz said:

Are you going to be running the mini split inside units inside the tents? If so all you need is a dehuey inside the tent and the co2 line and controller in each tent. What will the lighting source not that it would matter with a ac in the tent

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The shed is the lung room and the tents are inside the shed. The split and the dehu will run in the room and the tents will exchange air with the room. Lighting will be spider farmer SE1000W's 1 X for veg and 2 X for flower.

I'm wanting to know if I need to exchange the air inside the lung room/shed with the air outside or can I keep the whole thing sealed

Why don't you ditch the tanks and get a burner and cycle CO2 air into the tents keep the shed cool by using the mini split, adding co2 means you want very little to no exchange of air. But for a room that size ditch the tanks and get a burner.

Onextremebuzz said:

Why don't you ditch the tanks and get a burner and cycle CO2 air into the tents keep the shed cool by using the mini split, adding co2 means you want very little to no exchange of air. But for a room that size ditch the tanks and get a burner.

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Might get a burner once everything is set up. Can you run the burner inside the room or does it need to be run outside with the C02 line running into your room?

Kola_Kreator said:

Might get a burner once everything is set up. Can you run the burner inside the room or does it need to be run outside with the C02 line running into your room?

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A CO2 burner is kind of like a small gas heater that you hang from the ceiling. When the controller calls for CO2, the burner lights small jets that burn and emit the gas until your controller reaches your setting and then turns off. You run it inside your lung room. No CO2 line. Just CO2 emissions from combustion.

Kola_Kreator said:

Might get a burner once everything is set up. Can you run the burner inside the room or does it need to be run outside with the C02 line running into your room?

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There is no co2 line, the co2 falls, there's a gas line if the shed is a lung room and it's sealed and the air is flowing into the tent then the air should be close to the lung room

Thanks, I'll check that out. From what I know the burner is a lot more efficient than the bottles.

But the bottles are safer. Planning to have this thing rigger so I can leave it for weeks or even a month without needing to go inside. Probably could do both though. Bottles and a burner and switch to bottles if I'm going away.

I ran this 8 burner Titan with Spartan Controller in my 20x30 room.. no notice in heat or humidity with it. It would burn for about 40 min as the lights came on, then every hour or so for another 3 min burn, depending on where I had it set at (I.e. 1200-1400ppm) Propane fuel direct line from a remote 500 gallon tank... no notice in usage either. I share this tank with my primary residence. Do not vent... no need to. You'll just waste fuel bringing levels back up and making more heat in the process. Yield can vary, as I did a lot of experimentation, but you can expect 20-30% better weight with CO2.

DoubleAtotheRON said:

I ran this 8 burner Titan with Spartan Controller in my 20x30 room.. no notice in heat or humidity with it. It would burn for about 40 min as the lights came on, then every hour or so for another 3 min burn, depending on where I had it set at (I.e. 1200-1400ppm) Propane fuel direct line from a remote 500 gallon tank... no notice in usage either. I share this tank with my primary residence. Do not vent... no need to. You'll just waste fuel bringing levels back up and making more heat in the process.

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Thanks brother this was the reply I was after. I was thinking that there was no point in exchanging the air just needed somebody who is already doing it with success to confirm.

Huge colas in that photo. Your lowers under the canopy look bigger than most tops. I'm guessing that's a combo of plant training, heavy defol and the CO2

You run that temp and humidity target for the whole grow? My veg and flower will run at the same vpd so was thinking to target around 55 humidity and 82 temp

Kola_Kreator said:

Thanks brother this was the reply I was after. I was thinking that there was no point in exchanging the air just needed somebody who is already doing it with success to confirm.

Huge colas in that photo. Your lowers under the canopy look bigger than most tops. I'm guessing that's a combo of plant training, heavy defol and the CO2

You run that temp and humidity target for the whole grow? My veg and flower will run at the same vpd so was thinking to target around 55 humidity and 82 temp

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Thanks!.. I owned a commercial op for 4 years... till the market got stupid. But yeah, I would do a shit ton of training, strip my lowers, lollipop up, and make sure everything on top was getting light. I varied temps and RH following VPD, but I may have decreased RH towards the end.. like the last 2-3 weeks. Light intensity, CO2, temps, RH.. everything got dropped towards the end. You can search for "Compound HQ's Grows" and kinda see how I progressed this room over the past few years... long journal. Lot of bullshit in there too, but some educational stuff as well. I liked to experiment with different things.

DoubleAtotheRON said:

Thanks!.. I owned a commercial op for 4 years... till the market got stupid. But yeah, I would do a shit ton of training, strip my lowers, lollipop up, and make sure everything on top was getting light. I varied temps and RH following VPD, but I may have decreased RH towards the end.. like the last 2-3 weeks. Light intensity, CO2, temps, RH.. everything got dropped towards the end. You can search for "Compound HQ's Grows" and kinda see how I progressed this room over the past few years... long journal. Lot of bullshit in there too, but some educational stuff as well. I liked to experiment with different things.

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I'll definitely be reading through your journal. It would incredibly valuable for me to be able to see what you were doing as you progressed through a journey that I'm only just beginning.

I use LP gas for my kitchen stove and my wood-burning fireplace is also gas assist.

I had my builder bury a much larger LP tank than needed in my yard (500 gallons). I get a price break on the larger bulk purchase and I had the gas line run to my room. I also use a CO2 generator. With a room that big why the tents? Put a wall down the middle and divide that space! My room is also sealed. I never exchange the air.

HydroDawg421 said:

I use LP gas for my kitchen stove and my wood-burning fireplace is also gas assist.

I had my builder bury a much larger LP tank than needed in my yard (500 gallons). I get a price break on the larger bulk purchase and I had the gas line run to my room. I also use a CO2 generator. With a room that big why the tents? Put a wall down the middle and divide that space! My room is also sealed. I never exchange the air.

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Splitting the room is probably the best way to do things and I might look at it in the future but for now using tents is the easiest way. Plus I want to stay under 20 plants and if I'm flowering 6-8 plants at a time on rotation the big tent should be plenty of space for them.

Kola_Kreator said:

Splitting the room is probably the best way to do things and I might look at it in the future but for now, using tents is the easiest way. Plus I want to stay under 20 plants and if I'm flowering 6-8 plants at a time on rotation the big tent should be plenty of space for them.

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So . . . you solicit advice, acknowledge that it's good advice, and then are going to ignore the advice? Growing in a tent versus a sealed room is NOT the easiest. Growing in a tent is a restrictive pain in the arse! The room inside is very limited. Especially when you add lights, fans, filters, ducting, netting, pots, cords, dehumidifiers, limited vertical height, etc . . .

The cost of 2 quality tents could fund a portion of the CO2 generator, dehumidifiers, and the lumber necessary to build a wall. Make the flower portion of the room a little bigger than the veg room. Controlling the temperature, VPD, relative humidity, dew point, etc. can also be challenging. You are about to put a lot of heat-generating devices inside a very small space!

THIS is exactly the way I started about 20 years ago. I did it exactly once and will NEVER grow in a tent again. Many grow in a tent because they don't have a choice. It seems like you may. EVERY person who has no choice but to use a tent fantasizes about the day they'll be able to grow in a 20x15 sealed room. I designed my detached garage around a 20x15x9 sealed grow.

Again, if you can you should pull out all stops to avoid a tent and use this space to its maximum. You'll also need to mount that indoor portion of the mini split in the tent. And once you get ALL of this inside the tents . . . you'll understand why this isn't the preferred option.

I'm not being an @$$hole. I'm speaking from experience and wish I had someone who told me this a long time ago. It would have saved me a lot of $$, time, headache, and discontent!!!

could do what i did, i just did one open room. i keep a small tent/area outside the sealed room just for clones / bonsai mothers. my room isnt as big though. i have a 2ton mini split a/c, 105 pints total for dehus, and i have a natural gas co2 generator. same brand as aaron above but mine is the smallest they manufacture its a 2 burner. the room itself is framed with 2x4's, r12 insulation, 6 mil poly, and mold resistant drywall, flat white paint, white epoxy floor, 30 amp flip box, 20 amp circuit for dehus, 15 amp circuit for fans and whatever. custom insulated doors and removable panels with rubber gasket all the way around theres also dampers on springs that allow you to run the room sealed or unsealed depending on the time of year as well as exhausting the whole room outside per light cycle. if you click through my grow journal not sure which page its on but i show everyone with photos how i built the room step by step maby that will be helpful to you goodluck with the build

xox said:

could do what i did, i just did one open room. i keep a small tent/area outside the sealed room just for clones / bonsai mothers. my room isnt as big though. i have a 2ton mini split a/c, 105 pints total for dehus, and i have a natural gas co2 generator. same brand as aaron above but mine is the smallest they manufacture its a 2 burner. the room itself is framed with 2x4's, r12 insulation, 6 mil poly, and mold resistant drywall, flat white paint, white epoxy floor, 30 amp flip box, 20 amp circuit for dehus, 15 amp circuit for fans and whatever. custom insulated doors and removable panels with rubber gasket all the way around theres also dampers on springs that allow you to run the room sealed or unsealed depending on the time of year as well as exhausting the whole room outside per light cycle. if you click through my grow journal not sure which page its on but i show everyone with photos how i built the room step by step maby that will be helpful to you goodluck with the build

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That's a clean build mate. I wish I had half of the organisation skills that you've got. I'm definitely going to rethink my flower room plans. I don't see why I can't have an open area to flower in and the veg and clone tent inside the same room on a different light schedule.

HydroDawg421 said:

So . . . you solicit advice, acknowledge that it's good advice, and then are going to ignore the advice? Growing in a tent versus a sealed room is NOT the easiest. Growing in a tent is a restrictive pain in the arse! The room inside is very limited. Especially when you add lights, fans, filters, ducting, netting, pots, cords, dehumidifiers, limited vertical height, etc . . .

The cost of 2 quality tents could fund a portion of the CO2 generator, dehumidifiers, and the lumber necessary to build a wall. Make the flower portion of the room a little bigger than the veg room. Controlling the temperature, VPD, relative humidity, dew point, etc. can also be challenging. You are about to put a lot of heat-generating devices inside a very small space!

THIS is exactly the way I started about 20 years ago. I did it exactly once and will NEVER grow in a tent again. Many grow in a tent because they don't have a choice. It seems like you may. EVERY person who has no choice but to use a tent fantasizes about the day they'll be able to grow in a 20x15 sealed room. I designed my detached garage around a 20x15x9 sealed grow.

Again, if you can you should pull out all stops to avoid a tent and use this space to its maximum. You'll also need to mount that indoor portion of the mini split in the tent. And once you get ALL of this inside the tents . . . you'll understand why this isn't the preferred option.

I'm not being an @$$hole. I'm speaking from experience and wish I had someone who told me this a long time ago. It would have saved me a lot of $$, time, headache, and discontent!!!

Click to expand...

My plan was to have the tents inside the sealed room. Dehu's, AC and CO2 are in the sealed room not the tents and I would have 2 x 8 inch active exhaust fans + 2 X 8 inch active supplies. I was thinking that with this much air exchange all I would need to do is dial in the lung room and the tents should be the same.

I was leaning towards the tent mostly just because the lighting I'm thinking of using matches the canopy space of that tent. If I go to an open room I'll need to rethink the lighting plan.

But yeah the space of the open area solves more problems than it creates. Running all the feed lines and waste collection would be so much easier and the access to the plants would be way better.

BTW How do you calculate the heat load of a grow light and match it to the right size AC

Kola_Kreator said:

My plan was to have the tents inside the sealed room. Dehu's, AC and CO2 are in the sealed room not the tents and I would have 2 x 8 inch active exhaust fans + 2 X 8 inch active supplies. I was thinking that with this much air exchange all I would need to do is dial in the lung room and the tents should be the same.

I was leaning towards the tent mostly just because the lighting I'm thinking of using matches the canopy space of that tent. If I go to an open room I'll need to rethink the lighting plan.

But yeah the space of the open area solves more problems than it creates. Running all the feed lines and waste collection would be so much easier and the access to the plants would be way better.

BTW How do you calculate the heat load of a grow light and match it to the right size AC

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tally up the total watts of all the equipment in the room everything. 1 watt generates 3.41 btus/h.

so for example my 2 ton split does 24,000 btus of cooling in theory. that means in theory the max amount of watts it could theoretically cool is a max of 7038 watts.

however minisplits are variable condensers meaning they vary the amount of wattage used based on the amount of cooling required to maintain the set temperature so spending a few extra hundred dollars on over sizing your condenser will not cost you extra electricity if you dont use all the cooling capacity. however if your in an area where it gets very cold and you need a condenser that has defrost and is capable of operating in negative temperatures it would be important to note that the condenser becomes less efficient at cooling when the temperature is say -30c (im canadian convert it idk) and your Mitsubishi splits condenser is only rated for a max of -40c dont expect it to cool as well vs a hot sunny day with +20c outside. seriously if your gona spend the coin just get a good Mitsubishi split dont fuck around with anything else there the best for cold climates thats my biggest regret not putting one of those in and getting a cheaper one for my room

I grow in a 12x7x8 shed that is completely sealed. Lights out the c02 raises to pretty high levels. For the most part it’s not a problem until late flower. I noticed negative effects from excessively high co2 levels late flower so I ended up adding a fan and filter to exhaust co2 when lights out. Definitely a must in my situation. I’m not sure how sealed your shed is but if it’s anything like mine you may want to consider that variable.