Is there any reason to exhaust during CO2 enrichment?

[Inthewind]

I've looked for a few hours and can't find anything remotely close to an answer for this.

The question:

Is it necessary to frequently exhaust a grow room when enriching with Co2? Or can I just let it run 1300-1500 PPM for the total 18 hours? It would seem that I'm just dumping the Co2 out of the room if I was to exhaust. Hence the question.

I'm running CAP Controllers (Co2-2e and a PPM-1c) so keeping steady temps/RH and PPMs is a breeze.

I have a completely sealed room with couple of oscillating fans moving the air, but I'm not scrubbing it internally.

All help/comments are appreciated!

 

[budbrotato]

I would think as long as temp are fine you should be good, Most people vent to mitigate heat

 

[Rodrigo]

If you exhaust while feeding the CO2 then you're wasting resources, and venting CO2 to the outside of the tent/room is potentially very dangerous as we are not supposed to be breathing that. Think of an internal combustion engine, if the exhaust were to be always open the car would have little power and most of the mixture would escape right out before even being ignited (or in this case absorbed by the plant)

So what you need to do is to feed the CO2 only at the same time you water them, this is the best moment for absorption. Assuming they water themselves (timers and pumps) then set up the CO2 in the same fashion. If you water them manually the feed CO2 immediately after you're done watering and for a few minutes only (15-25 probably).

CAN you feed the CO2 continuously? yes of course, the plants will love it, but remember that the roots need oxygen so you cannot displace that much oxygen or it could be counterproductive. Also, there has to be an air exchange, ideally 4x the volume/hour. So you do NEED an exhaust and either an active or passive intake. Otherwise humidity is going to rise all the way.
I ran the tent for 1 night without the exhaust fan because I didn't have time to install it and humidity rose to 99%, there was condensation on all the walls and ceiling, luckily it was just the one night and after installation of the fan everything went back to where it should be.

If you feel that feeding CO2 continuously will be better and you'll have better yields (I don't use CO2 so I wouldn't know) then don't waste it by running the exhaust at the same time. use timers to alternate their operation, i.e. fan for one hour, CO2 for one hour, fan for one hour, so on and so forth.


Hope this helps,

Good luck and happy growing!!

 

[Rodrigo]

Most people vent to mitigate heat

You have to vent not only for heat issues (which can be dealt in other ways), you also have to vent because the girls need fresh air and to remove humidity and stale air.

 

[CronicHempHog]

you also know that supplemental co2 is only efficient if your temps are a bit high
like 85 and up if the temps are low your wasting resources
whats in the natural air is good enough as long as fresh air keeps coming in

 

[Inthewind]

Thanks for all of the replies

Some good info here for sure. Definitely got me thinking about other things such as the roots requiring o2. I've yet to see any specific mention of o2 for the roots in any of the literature I've been studying regarding Co2 enrichment, but it would only make sense.

My dilemma is that I have a fan for intake, one for exhaust (That are activated when heat gets >85 or a RH>60%) and a blower on the sealed cool tube. Nothing left to put on a timer to bring in fresh air.

I guess I could use my 6" Can Fan Max Fan to pull fresh air in via the line I have now thats got a 6" Active Air on it and take the Active Air off to use as the timed event.

I just keep thinking that if I clear the room and dump fresh air in there once an hour or so I'm wasting 400cf of Co2 every time I exhaust.

The room is dialed in between 75-85 and the RH has been stable between 40-60% and to be honest with you, after a slow start they are exploding!

This is my double bulb cool tube. One is a 430 and one is a 600. Both MH's

This is from December 7th. Popped on 10 November.

This is from today - December 13th.

I think its working!

 

[yuyo]

nice...me jealous
good work keep it up
take care and good luck

 

[1badbird]

I run a sealed room and CO2 generator along with an A/C unit. No fresh air coming in and no stale air going out. The plants thrive on CO2 and they convert that to oxygen so there's the fresh air. My 1 month old cuttings are 3' tall, like they're on steroids. I keep the temps at 85° @ the canopy and RH% at 45-50%. I'm also in and out of the room 3-4 times a cycle which exchanges air too.

I'm keeping my intake and exhaust fans in place as redundancy in the event of an A/C failure. I also have remote meters so I can see the room conditions from upstairs. Running higher temps leaves you a very small window for damage control if your A/C fails

WARNING: Keep an very active eye out for mites, they will thrive in this environment, just like the plants do.

 

[Inthewind]

Since I posted this thread I did pretty much the same as 1badbird; No exhaust, no intake, continuous Co2 at 1400-1500 ppm and they went crazy. From what they started out as to what they became, I will never go without C02 again. I recently stopped after around day 35 of 12/12 but now think I should have kept the Co2 going. I know people say it's useless after a certain time, but I didn't get the chance to test it out. Definitely next time for sure.

No mite issues and I only saw 1 or 2 of what I think to be fungus gnats but they disappeared and I never saw them again. I did find a couple of lady bugs just recently though!

Heres what they looked like initially, burnt tips from what I think was a combination of heat and PH:

From this:

To this:

Hows that for a pick up??

Co2, ya can't beat it!!

 

[1badbird]

I run a CO2, propane fired generator in a totally sealed environment with A/C, fans, dehumidifier & humidifiers so I can pretty much control my entire room with no outside ventilation.

The growing was amazing all the way up until the 3rd week of budding. The buds are plentiful but lacking some girth.

Does anyone know if it's possible to provide too much CO2 during budding?

 

[James123]

I've ran completely sealed grow rooms enriched with CO2. While the yields are still good this way the hybrid CO2 enrichment with air exchange works better. You get bigger nugs and more weight. I don't know the science of why this is 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.

 

[ICannaGrow]

The completely sealed grow room environment enriched with CO2 with no air exchange is an inferior technique to the hybrid system.

James,

Can you please explain exactly how this 'hybrid' system works? Do you run them simultaneously? Alternate CO2 and exchange? If the latter, how long for each? Do you have to modify the CO2 ppms doing the hybrid versus the sealed method?

 

[Stay fouced]

I've ran completely sealed grow rooms enriched with CO2. While the yields are still good this way the hybrid CO2 enrichment with air exchange works better. You get bigger nugs and more weight. I don't know the science of why this is 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.

What is the hybrid system because I’m gonna use a co2 generator and want to know all the information I can get before I set it up please it would help out a lot thank you

 

[013]

Hey Stay,

Welcome to 420, this is an old post that you have replied to... not sure if any of these people are still around.

 

[Rodrigo]

What is the hybrid system because I’m gonna use a co2 generator and want to know all the information I can get before I set it up please it would help out a lot thank you

A hybrid system means that you have a closed and sealed environment for co2 enrichment, with AC and humidifier and dehumidifier (the last two if it becomes necessary, it depends on where you live) but instead of being sealed all the time, once a day for an hour or two maybe, during lights out, you vent out all the air in the room via extraction fan and carbon filter (the smell is gonna be really concentrated if you run a sealed room) allowing for fresh air to enter.



To run a hybrid system you will need to invest in the following.



- Environmental controller; one that measures co2 concentration, temp, rh, etc. That'll run you about us$500 for a good one. There are of coursr cheaper options.

- Co2 tanks; preferably 2

- Co2 regulator

- small air hose with holes for delivery and distribution



You mentioned you were gonna get a co2 generator, I'm assuming you were thinking gas?

I would advice you against that, gas burners, while maybe efficient, create other issues; for one they increase temperature, so you will need to run an AC unit thay will work more than it has to, increasing your power bill. They are also dangerous, having fire burning seems to me more risky than it's worth.

Also they cause an issue with the rh that I don't understand but it will cause humidity to condensate and that may cause mold.



Co2 tanks and regulators are the way to go, but beware, they are not without danger, they are under a great pressure and dropping them or hitting them may cause them to burst or on extreme cases blow up. Handle with care, out of the way, and fastened to a wall or cabinet or whatever.

Also if possible, keep them out of the grow room.



- Extraction fan + carbon filter

- Fans to move the air around; while this is always a must, it is specially important when you use co2 because it sinks to the ground very fast so you need to keep blowing it upwards off the ground so the plants can use it.



That's all I could think about now.

Feel free to ask if you have any more doubts.

Happy to help.