sealed recirculating co2 grow box

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911reagan

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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. the problem some people have with sealed rooms with co2 is excessive temperatures. i believe plants can utilize up to 5000 fc at 90-85 farenheit co2 with a ppm less than 1200 at a relative humidity below 55% but above 50%. 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 3x3x5 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 about 2 inches above where you feel the top of the canopy will be . secure the puller fan on 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. also to reduce humidity , install an intermediate cylinder or box( coffee can works) and fill with silica beads and screens to keep them from moving. attach the pusher duct and the puller duct so the air goes through the cylinder pulling moisture from the duct. to reduce heat and vent problematic ethylene from the box we install a small fan on the ceiling of the box. this will be installed closest to the pusher fan side so that it sucks heat as well as ethylene out of the box while leaving room temp air and co2 in the recirc system. now this part is very important, we need to cut a small hole in the box so that the ethylene/ heat vent pulls fresh air from the hole and not from any leaks around the bottom of the box. if we neglected to cut this hole the negative pressure would force a leak anywhere on the box and it could pull air that is not enriched with co2 , defeating the purpose. the hole needs to be as close to the fan as possible. it should be on the same wall as the pusher fan above the canopy by at least 5 inches and within 1-3 inches below the ethylene/ heat exhaust fan. we basically want the fresh air to make it easier for the fan to pull heat ethylene out of the box, while keeping that same fresh air from entering the recirculating duct system.

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

as you can see ethylene is very light even lighter than air, naturally it will rise to the top , hot air as we know also rises to eliminate heat issues. the co2 being the densest of the 3 gases will stay in the bottom or pulled through the recirc system.

it is important for the heat/ ethylene extraction fan to have a lower cfm rating than the recirc sytem fans. this will ensure they are exhausting or recirculating their respective gases.


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

now 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

to create this you should need to spend =166$ (updated price)

1. 50 cfm ventilation fan =7$ for ethylene heat extraction ceiling of box (updated price) yes iv found at least 5 that cost 7$

2. 2 250 cfm 6 inch duct fans= 40$ total (updated price)

3. 6 ft 6 inch ducting = 12$

4. duct tape =3$

5. co2 monitor= 104$ (is also a temp/ humidity monitor) or you could buy a 166$ temp humidity co2 monitor timer and controller. i figured id give the cheapest monitor first for people who dotn want to use a burner or tanks

6. 500 grams silica beads-5$ (updated price)

with this method you can use the more ghetto methods of co2 production ie baking soda and vinegar, seeing as it is sealed save for the small exhaust fan up top, or yeast fermentation or yeast reproduction method(preferred)

with a co2 monitor you will easily able to see if this method has any validity and I hypothesize that it will save you money compared to a timed vent with other sealed grow rooms. I know 166 sounds expensive, but most co2 basic kits for a tank will cost you 60-120 and for a co2 sensor that releases co2 at a given ppm will cost 225- well over 1000$,not to mention the 200$ 20 lb tank you need as well. this setup will tell you every thing you need to know and wont waste co2 while making the baking soda vinegar method more effective and eliminating ethylene from the area

now with picture!!!!

co2 room.jpg

aw gee that's swell!
 
Recirculating air around in a closed loop is going to do nothing.
A small hole with 17 cfm fan to remove heat is not going to cut it.

There is no reason to have a push and pull fan setup.

Heat,humidity have to be exhausted no way around it.

Homemade Co2 buckets will not produce 1200 ppm and maintain it.
Your going to do much better with constant exhaust with good fresh air intake.
 
Brotha. You are way off. Your making it way too complicated. Duct tape? Lol.

Let me make it easy. Assuming you have a sheet rocked room that is not duct taped, but mudded and taped. A real room. Now,

Few grand=

-CO2 generator, preferably NG hooked to a constant supply
-Exhaust fan(scrubber) and filter, maybe two depending on room size
-CO2 controller
-Commercial De-humidifier
-Mini Split or Self contained frost box

Turn both on. Easy peezy. The hard part is actually growing the plants.
 
It would be great if you could set up a CO2 system for $224, but unfortunately, you can't. The fan you mention are duct booster fans--they are not meant to be used alone, but are made to be used in conjunction with larger fans on long duct runs. Homemade CO2 things, like baking soda and vinegar are not cost effective and do not produce 1200 ppm, and is not anywhere near constant. About the only way to effectively run CO2 is with bottled CO2 or a CO2 generator. It needs to be regulated with one of those expensive regulators you mentioned. I hate to see you waste even $224--what you are proposing is not going to work and be a waste of time, money, and effort.
 
Growdude said:
Recirculating air around in a closed loop is going to do nothing.
A small hole with 17 cfm fan to remove heat is not going to cut it.

There is no reason to have a push and pull fan setup.

Heat,humidity have to be exhausted no way around it.

Homemade Co2 buckets will not produce 1200 ppm and maintain it.
Your going to do much better with constant exhaust with good fresh air intake.

correction 50 cfm not 17. humididty will be adsorbed by silica beads. het will rise and be exhaust. upon completion i will test and show proof of co2, levels, temp and humididty. have you tried something simialer? pusher fan IS necessary to keep dense co2 moving on the grow box floor.
 
nouvellechef said:
Sometimes ya gotta find out the hard way in life.

the easy way isn't fun. silly. besides what do I have to lose? if my biggest problem is the exhaust fan isn't powerful enough, I simply buy a more powerful fan. not exactly "hard"
 
You have so many problems besides just the fan.

nouvellechef said:
Sometimes ya gotta find out the hard way in life.

Looks that way:rolleyes:
 
911reagan said:
the easy way isn't fun. silly. besides what do I have to lose? if my biggest problem is the exhaust fan isn't powerful enough, I simply buy a more powerful fan. not exactly "hard"

It isn't just the fans. Baking soda and vinegar simply is not going to produce enough CO2 to be useful. In addition, there is no way to control it.

You have time, money, and energy to lose. You would be better spending that $224 on more lighting rather than a cobbled CO2 set-up that is fraught with problems.
 
The Hemp Goddess said:
It isn't just the fans. Baking soda and vinegar simply is not going to produce enough CO2 to be useful. In addition, there is no way to control it.

You have time, money, and energy to lose. You would be better spending that $224 on more lighting rather than a cobbled CO2 set-up that is fraught with problems.


i did note that baking soda vinegar method is not optimal, the optimal method would be yeast reproduction cycle followed by fermentation, as the reproductive cycle of yeast yields 3 times the amount of co2 as fermentation.

whether you chose yeast, a burner, a co2 tank or baking soda vinegar are just small facets and preferences of each grower. if you were to use a stronger acid on baking soda it would yield even more co2. the possibilities are endless.

the point being if i can keep co2 levels stable with this setup, and prevent them from being sucked out( i will have the fans run in the empty box first and have the ppm tester at estimated canopy level to see if co2 stays in the room after 1,2,6,12, and 24 hours)it will be worth the time, energy , and small amount of money it costs.

and i have a 600 watt digital ballast setup i dont see the need for another one,especially in a 3x3 area

also of the 166$(updated price) 104$ is for the co2 meter alone, if you are really wary of sticking to sodium bicarbonate and acetic acid/ yeast sugar and starch method, you can always buy that 200$ cylinder, 60-120$ worth of connections and valves,166$ co2 meter timer fan controller etc and upgrade eventually.

most of the cost of my current setup are all things you would need anyways with a co2 setup, save the silica beads

and the cost to run an ac in the grow room will be 140$ for a 5000 btu unit as well as 36$ a month if your only doing 12/12. if you prefer a 24 hour veg cycle it will be 76$ a month.

for the fermentation method, a 3x3x5 grow room is 45 cubic feet

to figure out how much co2 we need to enrich the room to 1100 ppm we:

multiply cubic feet by .00075 to get .03375 cubic feet of co2 needed every 4 hours or .2025 per day.( remember atmospheric co2 is 350 ppm)

of course monitoring and testing are still necessary to ensure it stays in the 1000-1200 range this is an approximation for comparison purposes

1 lb sugar will ferment into .5 lb co2 and .5 lb alcohol. .5 lb co2 = 8.7 cu ft

8.7cu ft divided by .2025= 42.96 days of 1100 ppm co2(350+750)

yeast can be reused but mixing old yeast with new yeast yields good results.

cost for 1 year of fermentation= 4.36$ per year for a 25 lb bag of sugar which costs 13.76 $

not too bad when you figure a 20 lb co2 gets a refill between 20-54 $ depending on where you go to. my guy fills my 5 lber for 6 $ and iv been going to him for years for my kegmeister 9000 refills. now take into account you're going to run out of co2 after about a week with a 20 lber thats 20$ x 52= 1040$ per year, even with a burner that will end up being 300$ a year, and thats for a 3x3x5 growbox.

now im not going to get into the subtle nuances of aerating the wort( great for co2 but as with sugar(please invert me) too much can damage the cell walls of the yeast especially during propagation phase) but i provided the above calculations as a cost example.

and dont forget , a good ipa goes great with a piece filled with blueberry. the hoppiness of the ipa offsets the fruitiness of the smoke. might as well kill two birds make co2 and some brew
 
nouvellechef said:
Brotha. You are way off. Your making it way too complicated. Duct tape? Lol.

Let me make it easy. Assuming you have a sheet rocked room that is not duct taped, but mudded and taped. A real room. Now,

Few grand=

-CO2 generator, preferably NG hooked to a constant supply
-Exhaust fan(scrubber) and filter, maybe two depending on room size
-CO2 controller
-Commercial De-humidifier
-Mini Split or Self contained frost box

Turn both on. Easy peezy. The hard part is actually growing the plants.


i will say this, i like the way you think. but iv never been the keep it simple stupid type of person
 
911reagan said:
now take into account you're going to run out of co2 after about a week with a 20 lber thats 20$ x 52= 1040$ per year, even with a burner that will end up being 300$ a year, and thats for a 3x3x5 growbox.

Actually a 20 lb tank would last 437 days.
and a 5 gal propane tank lasts 3.69 years.

A 45 cubic foot area (yours) @ 1 CFH=3 min on time. At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 174.8 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 540 hours. What you read was the on time total.

This is the TOTAL time the tank will last.

Also the 437 days was figured with the recomended air exchange of every 3 hours.
So to make it simple for you, every 3 hours the tank runs for 3 min, with a tank lasting 174.8 hours @ 1 CFH.
Total of 24 min run time per day /144.8 hours total tank time = 437 days.
 
"...whether you chose yeast, a burner, a co2 tank or baking soda vinegar are just small facets and preferences of each grower. if you were to use a stronger acid on baking soda it would yield even more co2. the possibilities are endless..."

That simply is not true. The only effective way to supplement CO2 is with a CO2 tank or a CO2 generator. The source of the CO2 is not a "small facet" as both the yeast method and the baking soda method are ineffective. And the CO2 MUST be regulated.

I do not want new growers going out and spending over $200 for something that is not going to work. So, new growers, this will not work and is a waste of time, effort, and money.
 
Thank you growdude,

Also... Yeast reproduces and dies off quickly, at its own rate. I'm a distiller, and thinking that a 25 pound bag of sugar will ferment for an entire year producing a ppm that high, with the setup your talking about... is silly.

The fermentation process with temps of around 80 degrees with a sugar wash is a vigorous ferment for three days tops and it dwindles from there. That's with a proper specific gravity mixing two pound of sugar per one gallon of water.


This is so redic dude, no offense... But your going about this all wrong.

Why try and reinvent the wheel? It works fine! This contraption will be nothing more than a waste of time and whatever money... But if that's how you learn go for it.

Try switching to hydro if you want better yields. There is so much I could say but I think I made my point.


Welcome to the site BTW ;)
 
Might I add , your going about this as an engineer would... A person who understands the concepts yet can't put it together in their head that it won't work "in real life" and not just "on paper".

And I mean that in a good way.
 
trillions of atoms said:
Might I add , your going about this as an engineer would... A person who understands the concepts yet can't put it together in their head that it won't work "in real life" and not just "on paper".

And I mean that in a good way.

That makes me laugh. I have gotten blue prints from engineers that simply were not plumbable. After arguing with one homeowner about the impossibility of the plans, I finally gave in and said that I could work from the plan, but I had really thought they wanted their master toilet to flush.
 
Growdude said:
Actually a 20 lb tank would last 437 days.
and a 5 gal propane tank lasts 3.69 years.

A 45 cubic foot area (yours) @ 1 CFH=3 min on time. At this flow rate:
If you are using a 20 pound CO2 bottle with a regulator, it will last 174.8 hours.
If you have a CO2 Generator a 5 gallon propane tank will last 540 hours. What you read was the on time total.

This is the TOTAL time the tank will last.

Also the 437 days was figured with the recomended air exchange of every 3 hours.
So to make it simple for you, every 3 hours the tank runs for 3 min, with a tank lasting 174.8 hours @ 1 CFH.
Total of 24 min run time per day /144.8 hours total tank time = 437 days.

and that is the equivalent of doing nothing. a 20 lb tank wont last more than 2 weeks if you're doing it right
 
The Hemp Goddess said:
"...whether you chose yeast, a burner, a co2 tank or baking soda vinegar are just small facets and preferences of each grower. if you were to use a stronger acid on baking soda it would yield even more co2. the possibilities are endless..."

That simply is not true. The only effective way to supplement CO2 is with a CO2 tank or a CO2 generator. The source of the CO2 is not a "small facet" as both the yeast method and the baking soda method are ineffective. And the CO2 MUST be regulated.

I do not want new growers going out and spending over $200 for something that is not going to work. So, new growers, this will not work and is a waste of time, effort, and money.

i did not know this was the beginner forum.
 

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