# 100% Sealed room with CO2 enrichment, vent dump during lights off ??



## horndog (Sep 4, 2014)

Difference of opinion.

I for one believe that a grow room that is 100% sealed and enriched with CO2 DOES NOT NEED A VENT DUMP DURING THE OFF CYCLE, if ever during a grow. I have a friend who believes that it is beneficial to vent dump during the off cycle to move out any build up of excess CO2 and ethanol (ok i add the ethanol part). I totally disagree, when you use a controller and monitor and enrich to your target ppm point , say 1100ppm then there is no build up of CO2. Since you don't enrich during the off cycle what would be the benefit? Plants put off oxygen during the on cycle and put off CO2 during the off cycle. I wanted to post this questions so we both can see for ourselves what the general consensus is. 

We are not discussing temperature, humidity, during an emergency or anything other than for CO2 here, so please stay on topic friends.

On cycle = lights on period
Off cycle = light off period
you would be surprised some people don't get the whole on/off thing.....lol


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## AlecTheGardener (Sep 4, 2014)

horndog said:


> Difference of opinion.
> 
> I for one believe that a grow room that is 100% sealed and enriched with CO2 DOES NOT NEED A VENT DUMP DURING THE OFF CYCLE, if ever during a grow. I have a friend who believes that it is beneficial to vent dump during the off cycle to move out any build up of excess CO2 and ethanol (ok i add the ethanol part). I totally disagree, when you use a controller and monitor and enrich to your target ppm point , say 1100ppm then there is no build up of CO2. Since you don't enrich during the off cycle what would be the benefit? Plants put off oxygen during the on cycle and put off CO2 during the off cycle. I wanted to post this questions so we both can see for ourselves what the general consensus is.
> 
> ...


I have found no benefit to venting sealed co2 enriched grow rooms.

With full control of my grow room's climate there is no need for venting unless something like catastrophic equipment failure causes it.

If humidity, co2, temperature, and proper in-room air movement (osc. fans), and scrubbing are provided adequately, I have not vented a sealed room before during any part of the light cycle or growth cycle.

Only in emergencies such as dehumidifier failure or air conditioning failure have I ever had the need.


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## horndog (Sep 4, 2014)

I agree 100%, thank you for chiming in ATG. 

Come on guys you aren't giving blood here, just you opinion.


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## horndog (Sep 5, 2014)

I am wondering how beneficial this really is or is it unnecessary all together.

I guess one of the question would be:

Does the air in a sealed environment get stale. Personally i believe the fact that CO2 is being introduced in is to keep it from being just that.

Does the plants need or use fresh oxygen during the off cycle.

My understanding is that :
during the on cycles plants take in CO2 and produce oxygen
during the off cycle just the reverse

All opinions count, I am looking to learn.........not to argue a point........so no judgement here.

For those who vote to vent, could please state why or your reasoning behind that strategy. I'm trying to get a better understanding.


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## ASMALLVOICE (Sep 5, 2014)

My flower room is sealed so as to use CO2 in the future, But I do have an exhaust and intake setup just incase I need to vent for whatever reason. My room is 100% automated. I am planning on using CO2, because I believe the benefits are tangible.

I agree that a sealed room is the way to go, as it is more stealthy for sure. As long as there are no equipment failures all is well, if there is, the room will need to breath a little till the repairs are made, so I think the system should be in place to do so.

Peace and Great Grows

Asmallvoice


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## superstoner1 (Sep 5, 2014)

The whole idea behind a sealed room is total control and no vents.


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## chuck estevez (Sep 5, 2014)




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## ASMALLVOICE (Sep 5, 2014)

superstoner1 said:


> The whole idea behind a sealed room is total control and no vents.


Not 100% so, if you have ever worked in a clean room environment, you would see the need to have an alternate means of ventilation in case of mechanical failure, which exists in everyone's world from time to time. I use D3 dampers to isolate and can control the pressures in my room from sucking the door closed to blowing it open, if I so choose.

It is all about the control, until something breaks. If you live in a perfect world where there are no mechanical failures, then more power to you...lol

Peace and Great Grows

Asmallvoice


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## anzohaze (Sep 5, 2014)

Agree with above I run a sealed room with intake and exhaust capability. My burner cuts off 45 minutes prior to lights shutting to lower co2 levels. once lights go off I vent for 15 minutes at a time. I vent an hour after lights (8 at night) vent again at 1 am and then again at like 6am. When I veg in the room I cycle intake and exhaust fans every so often to keep from running my burner in veg amd to keep co2 in room


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## Aeroknow (Sep 6, 2014)

I also build sealed rooms able to be vented also
Put dampers on intake/exhaust ducting.
IMO, the versatility of it,
makes for the ultimate growroom!
I guess, you could call it a hybrid growroom


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## SnapsProvolone (Sep 6, 2014)

Venting during lights off can be a n energy efficient method of dealing with humidity provided your ambient RH isn't too high and temperatures are acceptable. Mighty big if for some.


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## Sand4x105 (Sep 6, 2014)

horndog said:


> .........................
> 
> Come on guys you aren't giving blood here, just you opinion.


I gave blood last week....
and will again 56 days after....
It's fun way to help humanity...
Google [or Bing]:

*The Health Benefits of giving blood....*

Your mind will be blown....

Pot heads unite.... give blood.... it's fun and easy....live longer... be more healthy....88% less chance of a heart attack or CANCER!
So if you have heart issues in your family history, or cancer.... Just saying I have found the fountain of youth....Give Blood...


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## Aeroknow (Sep 6, 2014)

Sand4x105 said:


> I gave blood last week....
> and will again 56 days after....
> It's fun way to help humanity...
> Google [or Bing]:
> ...


I can't give blood. Tattoos and drugs
Hey! What is this thread about?


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## SnapsProvolone (Sep 6, 2014)

Sand4x105 said:


> I gave blood last week....
> and will again 56 days after....
> It's fun way to help humanity...
> Google [or Bing]:
> ...


Wife got all mine already.


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## soma9490 (Sep 6, 2014)

I run a sealed room and never vent. Mines automated aswell . However mines a "hybrid " . In the winter I use the vents to cool the room. And co2 monitor with tanks. Everything works great.


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## Aeroknow (Sep 6, 2014)

soma9490 said:


> I run a sealed room and never vent. Mines automated aswell . However mines a "hybrid " . In the winter I use the vents to cool the room. And co2 monitor with tanks. Everything works great.


Nice! I like your style. Welcome to the forums

That is what I usually do also. Last winter, I switched to vented, and I fired up some more lights. Power bill was about the same. Why not do that rite? (i have extra space in my flower room)


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## horndog (Sep 9, 2014)

Chuck es.....
Thank you for the video, informative.

As far as the room having the capabilities to vent in case on an emergency is smart to incorporate.
Using a strategy of vent during the off cycle is a different topic all together and I'm not seeing the benefit here. If I am running a sealed room then I have a dehumidifier. If I have a dehumidifier than I always can control that aspect and don't need to open a window sort to say to control it. So what again is the benefit to the grow, the plants to include an EXTRA unnecessary step for the sake of what.....? I get the economical savings here, but I am looking at it from a total superior grow stand point, not the economic factors.

Besides all that, thank you guys for the feedback....most helpful


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## kulakush (Sep 1, 2017)

While you may get decent results by running CO2 and not ventilating your sealed room, you will hit less weight than if you had properly ventilated as well. The key is to maintain your CO2 levels but slowly vent out the air with a continuous exhausr fan using a dimmer controller or by exhausting every few hours for 10 mins. You must rid the bad gases that form in a sealed room especially if you are burning CO2. You may spend a little bit more on CO2 but the extra weight from the bigger buds you will get trumps that cost. 

Here is why: Because of a plant biproduct and burn biproduct gas called ethylene. Ethylene known as the death hormone acts at trace levels throughout the life of the *plant* by stimulating or regulating the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves. Excess ethylene will cause your buds to rippen faster in the last few weeks and will stunt your bud growth. Dying leaves in the last few weeks produce ethylene. Burning CO2 creates ethylene as well.

Plants consume CO2 in the process of photosynthesis and convert it to sugar. Oxygen is a waste product of this reaction, in that water is split to form hydrogen and oxygen. The plant uses the hydrogen to produce ATP. This process is only occurring in the day when there is light. However, at all times, the plant is respiring, just like people. They need oxygen for the metabolic process and produce CO2 as a waste product. Indoor closed grows also produce

Ethylene . This is a plant hormone in a gas form that can have negative effects on flowering plants { specially when the plants are closer to finish]. Any dying and decomposing plant mater can produce Ethylene.

Ethylene damage can be hard to see if you dont know what your looking for and can have very negative effects on your yield .Its nice to shut down the ac at night and flush out all contaminants and start fresh every morning. Some people have good success periodically flushing out there rooms of co2 during the day. Just google ethylene and flowers and you'll see why


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## kulakush (Sep 8, 2017)

While the yields are still good with CO2 enrichment and no air exchange in a sealed environment, the hybrid CO2 enrichment with air exchange works better. You get bigger nugs and more weight. I don't know the exact science of why this occurs but I can tell you from experience of doing it both ways and my best results have been using both CO2 enrichment and air exchanges. My og kush plants thrive this way. For example when I ran CO2 in an enclosed room that uses a scrubber to clean the recycled air, I would average around 2.3-2.5 pounds per gavita fixtures. The nugs do get dense but not very big compared to the hybrid system. When I enriched with CO2 with air exchange I started hitting 3+ pounds per gavita fixture. My og kush nugs were bigger and did not rippen so quick. All my buddies that are getting over 3 a light are doing the same. The completely sealed grow room environment enriched with CO2 with no air exchange is an inferior technique to the hybrid system. 1st photo is the the top bud of my og strain using the hybrid system. The second photo is a top nug with no air exchange running CO2 in a sealed environment where the air is recycled and only scrubbed.


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## kulakush (Sep 8, 2017)

Found a good article that explains why you should also exchange your air in a sealed environment with CO2 enrichment. It comes down to excess ethylene build up and proper oxygen levels. Makes sense, my worst producing sealed rooms where the ones that I used a propane CO2 burner. The excess ethylene made my leaves yellow prematurely and my nugs were small dense and very crystallized. Decent weight still pulled over 2 a light but not my best grow.

http://www.cannabisbusinesstimes.com/article/bad-gas/


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## nopifarms (Feb 22, 2020)

kulakush said:


> While the yields are still good with CO2 enrichment and no air exchange in a sealed environment, the hybrid CO2 enrichment with air exchange works better. You get bigger nugs and more weight. I don't know the exact science of why this occurs but I can tell you from experience of doing it both ways and my best results have been using both CO2 enrichment and air exchanges. My og kush plants thrive this way. For example when I ran CO2 in an enclosed room that uses a scrubber to clean the recycled air, I would average around 2.3-2.5 pounds per gavita fixtures. The nugs do get dense but not very big compared to the hybrid system. When I enriched with CO2 with air exchange I started hitting 3+ pounds per gavita fixture. My og kush nugs were bigger and did not rippen so quick. All my buddies that are getting over 3 a light are doing the same. The completely sealed grow room environment enriched with CO2 with no air exchange is an inferior technique to the hybrid system. 1st photo is the the top bud of my og strain using the hybrid system. The second photo is a top nug with no air exchange running CO2 in a sealed environment where the air is recycled and only scrubbed.



Old post but was interested in when the air exchange happened? was it temperature based? or just based on a schedule? Looking into a hybrid combo. Thanks in advance


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## ChrispyCritter (Feb 22, 2020)

Ha! I didn't even look at the date and I just voted. It's no wonder my wife gets mad at me all the time.


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## Renfro (Feb 22, 2020)

I'll chime in too just for shits and grins since ppl will be looking at the thread now.

For me it depends greatly on the amount of water in the outside air. We don't wanna blow in air that is way too humid. We also want to prevent the temperature from dropping too far if the ambient air is very cold.

Remember cold air = dry air.

A vent cycle at lights out can really help with the associated RH% spike that many grows tend to encounter when biomass is very large. This of course depends on the ambient air conditions.


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