Setting up CO2, humidity question.

Carthoris

Well-Known Member
I am setting up my CO2. Essentially I am building a little room( 2 foot x 2 foot) around a window unit(12k btu). The cold air is piped into the bottom of the grow, and the hot air is sucked out of the top and pushed back into the room. I have it currently piped in already, but it draws its air from the surrounding room as I don't have the CO2 on. I have about 40% humidity at 75 degrees. The grow area is a 4x4 secret jardin tent. I have a large dehumidifier that I can run if I build the box large enough to accommodate it. Is it necessary though? I am going to raise the temperature to 85 in the grow. This should actually cause the AC to dehumidify the grow more efficiently. At least, that is my assumption. Not only would the dehumidifier cause me to make the box bigger and run lines for the waste water output, it would also take up valuable grow room space. I have to store my collection of grow room equipment somewhere, ya know? Anyone have any input before I build the AC box in a few hours?
 
Humidity is to low already Canabiss is a tropical plant I run mine at 75% humidity. With that much a/c in such a small area it will pull the moisiture out in a hurry I would add a humidifer to to get some back into the air also 85d is to hot unless your running co2 evean then 80 is the max. You will give the plants heat stress and they will go into survial mode. IMO
 

Endur0xX

Well-Known Member
what!!? best RH for cannabis is around 40 I thought...if the garden is not up nd running yet, expect the RH to rise significantly...
 

Carthoris

Well-Known Member
what!!? best RH for cannabis is around 40 I thought...if the garden is not up nd running yet, expect the RH to rise significantly...
I was hoping the AC would take care of it without the dehumidifier. I have both though. It was hovering between 50-60% humidity. I went ahead and added the dehumidifier into the loop.
 

stems&seeds

Active Member
Humidity is to low already Canabiss is a tropical plant I run mine at 75% humidity. With that much a/c in such a small area it will pull the moisiture out in a hurry I would add a humidifer to to get some back into the air also 85d is to hot unless your running co2 evean then 80 is the max. You will give the plants heat stress and they will go into survial mode. IMO
No offense but everything quoted above is false. 75% humidity will ensure mold growth in flower. And 80 is not too hot for co2. Keep your humidity between 40-50%, err on the low side in late flower if ya want. If your using adequate co2 than 80-85 degrees is appropriate.
 

Carthoris

Well-Known Member
My question was more about whether the ac would be able to keep up with a 4x4 tent on its own.

I have been running the tent for the last couple days with co2. I let it run over 90 one day and it hit 72% humidity, and then turned it down to 85 hoping that the AC being on more would dehumidify the grow better. It kept it in the 60's for humidity. The plants seemed to love both temps. Since 85 was as low as I was willing to go I went ahead and installed the dehumidifier. I set it on 'normal' and now its at 50 humidity. I might drop it a little more after the buds start to form and become dense.
 

burrr

Well-Known Member
Some window ac units DO NOT do any dehumidifing, and just blow the condensate back into the cold room.
 

Carthoris

Well-Known Member
Some window ac units DO NOT do any dehumidifing, and just blow the condensate back into the cold room.
I have never seen an AC that didn't dehumidify, though I suppose anything is possible. Running hot air over cold coils dehumidifies the air. When hot air is cooled, it can no longer hold as much humidity. So the humidity falls out of the air when it goes through the cooling coils. That water isn't sprayed back into the air or anything. It drips out the back of the unit or into a container.
 

burrr

Well-Known Member
I have never seen an AC that didn't dehumidify, though I suppose anything is possible. Running hot air over cold coils dehumidifies the air. When hot air is cooled, it can no longer hold as much humidity. So the humidity falls out of the air when it goes through the cooling coils. That water isn't sprayed back into the air or anything. It drips out the back of the unit or into a container.
On the one I recently disassembled the condensate water did not drip out the back. The unit had a pan under the cooling coil that the fan blew across. the condensate would just get blown back in the air in between cooling cycles.
 

apbx720

Well-Known Member
My question was more about whether the ac would be able to keep up with a 4x4 tent on its own.

I have been running the tent for the last couple days with co2. I let it run over 90 one day and it hit 72% humidity, and then turned it down to 85 hoping that the AC being on more would dehumidify the grow better. It kept it in the 60's for humidity. The plants seemed to love both temps. Since 85 was as low as I was willing to go I went ahead and installed the dehumidifier. I set it on 'normal' and now its at 50 humidity. I might drop it a little more after the buds start to form and become dense.
veg rh can be in the 60s. late flower u should keep yr ideally from 40-50%. imo 85deg f should be about as high as u wanna go. i wouldnt go much higher than that
 

Carthoris

Well-Known Member
On the one I recently disassembled the condensate water did not drip out the back. The unit had a pan under the cooling coil that the fan blew across. the condensate would just get blown back in the air in between cooling cycles.
The fan blows both ways. I've had one like that. It still dehumidifies.
 
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