CO2 & Humidity

MadeInUSA

Well-Known Member
Hi everyone,
I've got a battle on my hands with humidity on a CO2 grow during fall season when it's too cool to use AC but not cold enough to run the heat.
The good of CO2 is my plants are growing like crazy. Aggressive growth is how I would describe it.
The bad is my closed tent humidity is out of control. My active journal (signature) on page 3 shows the issue. RH is 99%. To combat the issue I'm running the in/out exhaust fans every 2 hours for 6 min, and for 6 hours during lights out. It gets RH down to 64%. Right now the home heat/AC is not running, and outdoor humidity is at 65%.

The reason I am posting is to see if others have advice on this. With CO2 the rate of transpiration in the tent is off the chart. To battle this, I'm buying another tent pole fan to blow down on the canopy, an addition to the one I have blowing underneath the canopy. Also I have purchased (2) new 20 event timers to replace the 8 event timers I have, with the idea of venting for 5 minutes every 60 min (cycling off my CO2 during the time the vent is running to conserve the CO2). I bought a water pump to pump out excess standing water from feedings.

I would really like to run CO2 in flower but bud rot has me really worried. I'm at late stage veg and want to flip to flower in 10 days. If I can get the heat turned on (come on, send me cold weather!) and we can close up the house tight, I know I can get this under control.

Worse comes to worse, I can just turn off CO2 if I can't dial this in, run my in/out fans 24/7 and I'll probably be good.

Tossing in some photos that show the tent walls.
IMG_338121.JPG

IMG_338222.JPG

IMG_338322.JPG
 
you need a dehumidifier inside the grow, I personally keep mine outside run with vent, running in line with 14000 btu ac inside temps bounce 79°-82°,72-75° night cycle. rh day cycle 65-70% night cycle 45-50% co2 1500ppm 20lbs tank lasts about 10-11 days depending how often I work inside. sry 4.5x4.5x7 grow 1000w hps 9 pots on drip system an nutes 2.3 e.c.or 1150 ppm
 
Hi everyone,
I've got a battle on my hands with humidity on a CO2 grow during fall season when it's too cool to use AC but not cold enough to run the heat.
The good of CO2 is my plants are growing like crazy. Aggressive growth is how I would describe it.
The bad is my closed tent humidity is out of control. My active journal (signature) on page 3 shows the issue. RH is 99%. To combat the issue I'm running the in/out exhaust fans every 2 hours for 6 min, and for 6 hours during lights out. It gets RH down to 64%. Right now the home heat/AC is not running, and outdoor humidity is at 65%.

The reason I am posting is to see if others have advice on this. With CO2 the rate of transpiration in the tent is off the chart. To battle this, I'm buying another tent pole fan to blow down on the canopy, an addition to the one I have blowing underneath the canopy. Also I have purchased (2) new 20 event timers to replace the 8 event timers I have, with the idea of venting for 5 minutes every 60 min (cycling off my CO2 during the time the vent is running to conserve the CO2). I bought a water pump to pump out excess standing water from feedings.

I would really like to run CO2 in flower but bud rot has me really worried. I'm at late stage veg and want to flip to flower in 10 days. If I can get the heat turned on (come on, send me cold weather!) and we can close up the house tight, I know I can get this under control.

Worse comes to worse, I can just turn off CO2 if I can't dial this in, run my in/out fans 24/7 and I'll probably be good.

Tossing in some photos that show the tent walls.
IMG_338121.JPG

IMG_338222.JPG

IMG_338322.JPG

Beautiful plant great job just a small piece of advice, I keep my Co2 tank outside room Bc someone else might have had it in there Grow and I don't want there mites or pests, I run 1/4" tubing
 
you need a dehumidifier inside the grow, I personally keep mine outside run with vent, running in line with 14000 btu ac inside temps bounce 79°-82°,72-75° night cycle. rh day cycle 65-70% night cycle 45-50% co2 1500ppm 20lbs tank lasts about 10-11 days depending how often I work inside. sry 4.5x4.5x7 grow 1000w hps 9 pots on drip system an nutes 2.3 e.c.or 1150 ppm

That's great advice, thank you madframermrc. I have gotten things much better with the humidity now, however your idea needs to be my next step. The only saving grace I have going for me now is that it's winter and very low humidity now which makes the situation manageable. Now, my worst day humidity wise is the 1st 24 hours after I water or feed, whereas when I originally took these pics, everyday was a bad day humidity day lol.
 
Beautiful plant great job just a small piece of advice, I keep my Co2 tank outside room Bc someone else might have had it in there Grow and I don’t want there mites or pests, I run 1/4” tubing

Yes, that is great advice, thank you bignugz420. I have heard of that also, when I was watching some utubes on CO2, and it's a very real thing, carrying other's pests into your tent with tanks. Luckily, I bought my tank new, unused. I am fortunate enough to be able to refill this tank so I know the conditions it is always under. Otherwise, you are right, it'd be outside my tent.

Thanks for the plant comments, good nutes and CO2 help alot to make them florish.
 
you need a dehumidifier inside the grow, I personally keep mine outside run with vent, running in line with 14000 btu ac inside temps bounce 79°-82°,72-75° night cycle. rh day cycle 65-70% night cycle 45-50% co2 1500ppm 20lbs tank lasts about 10-11 days depending how often I work inside. sry 4.5x4.5x7 grow 1000w hps 9 pots on drip system an nutes 2.3 e.c.or 1150 ppm

Wow you have a nice setup going for you madframermrc. My RH swings pretty wide 40-80% in a 24 hr period because I run my intake with carbon and my vent fan with carbon the full 12 hours at about 75% speed and the air dries out pretty good. During the light cycle when the CO2 runs, every 30 min the CO2 runs with no fans (caps at 1500 ppm, then auto shutoff), then I power down the CO2 and turn on the intake/vent fans to lower the RH to from 80% to 50% in 5 min. I do that 24 times in a 12 hr period. Stretches my CO2 usage big time turning off the CO2 when venting out. For CO2 closed tent systems I feel air movement is key. I have 1 fan blowing up from the floor through the canopy, and 2 side fans to keep the sides dry. The back of my tent still needs another fan, and I should be venting every 15 min probably. I defoliated which helped quite a bit.
 
Wow you have a nice setup going for you madframermrc. My RH swings pretty wide 40-80% in a 24 hr period because I run my intake with carbon and my vent fan with carbon the full 12 hours at about 75% speed and the air dries out pretty good. During the light cycle when the CO2 runs, every 30 min the CO2 runs with no fans (caps at 1500 ppm, then auto shutoff), then I power down the CO2 and turn on the intake/vent fans to lower the RH to from 80% to 50% in 5 min. I do that 24 times in a 12 hr period. Stretches my CO2 usage big time turning off the CO2 when venting out. For CO2 closed tent systems I feel air movement is key. I have 1 fan blowing up from the floor through the canopy, and 2 side fans to keep the sides dry. The back of my tent still needs another fan, and I should be venting every 15 min probably. I defoliated which helped quite a bit.
So how long does a 20lbs tank last you with venting?
 
So how long does a 20lbs tank last you with venting?

Personally I don't vent if running Co2 , I seal room and bring air into it on a timer just to cool it down, but other than that I don't exhaust until lights out and Co2 isn't on I like having a sealed room
 
So how long does a 20lbs tank last you with venting?

So far, I have been growing since 9/1/17 and the tank is not empty yet. I think it should last me the entire grow (another 4-5 weeks from now) With these tanks you can't look at the guage to determine fullness, you know you are empty when your CO2 meter stops registering regular 1500 ppm.
 
Personally I don’t vent if running Co2 , I seal room and bring air into it on a timer just to cool it down, but other than that I don’t exhaust until lights out and Co2 isn’t on I like having a sealed room

Thats basically what I do too, sort of. My previous post explains my process, however I do agree 100% with bignutz420, I like having a sealed room - not only for the CO2 but to control the smell, with 4 plants in a 4x4, its very strong once you start flowing. If stealth is important to you, seal the room and vent it using a carbon filter, it makes all the diff in the world and worthwhile. Even sealed grow tents will bleed smell to a small degree when the fans are not running during daylight CO2 runs
 
So far, I have been growing since 9/1/17 and the tank is not empty yet. I think it should last me the entire grow (another 4-5 weeks from now) With these tanks you can't look at the guage to determine fullness, you know you are empty when your CO2 meter stops registering regular 1500 ppm.
Wtf I only get about 10-11 days on a 20lb tank at 1500ppm 4.5x4.5x84 sealed tent am I doing something wrong lol.
 
I am a newbie here and can't start new threads yet.. Is there such a thing as too much CO2 for plants?? It will be hard to terraform Mars if so.


There is concern among our team here that non vented propane heaters will kill plants in a greenhouse... My theory is they shoul,d be fine..

Are there any mechanical/electrical gas valve thermostats that can be put in line to a an infrared heater?

Thanks if you can reply.. looking forward to hanging with you all here.. I am in Calaveras County and active in the Cannabis Industry
 
I am a newbie here and can't start new threads yet.. Is there such a thing as too much CO2 for plants?? It will be hard to terraform Mars if so.


There is concern among our team here that non vented propane heaters will kill plants in a greenhouse... My theory is they shoul,d be fine..

Are there any mechanical/electrical gas valve thermostats that can be put in line to a an infrared heater?

Thanks if you can reply.. looking forward to hanging with you all here.. I am in Calaveras County and active in the Cannabis Industry

I believe the carbon monoxide from the heaters would build up and kill everything and EVERYONE in the space. Would co2 burner be an option as they create heat as well as co2 without the need for venting?
 
I have an answer to "how long does a 20 lb CO2 tank last"? question I've been asked several times. Using most restrictive use methods in a closed 4x4 tent:
* Electronic regulator connected to a CO2 monitor that limits to 1500 PPM with auto turn off at night
* During Veg, run CO2 continuously the 18 hr lights on cycle CO2 turns off when it hits 1500ppm, then kicks back in when needed); only vent tent when lights off (when Co2 is auto shutoff); downside became humidity buildup happening, hard to control. I felt the gamble was OK without budding and 2 tent pole fans and 1 on the floor moving air. CO2 is a heavy gas that likes to sit at the bottom of the tent.
* During flower, running 30 min on CO2 with no exhaust fans; running 5 minute exhaust cycle (with CO2 off) to lower humidity, then repeating that cycle continuously during the 12 hour lights on

Doing all that, a full 20 lb tank lasted me 107 days. IMO I think the investment in the regulator and monitor (appx $300 US) paid for itself in a single grow (versus not having those) as I have heard a tank lasting appx 10 days using flow rate to space determination and larger space or tents.....for me a tank refill using my own tank is $29...PLUS, and this is very important, you should not run CO2 with lights out, you will kill your plants.

I love CO2, it's a gas!
 
I have an answer to "how long does a 20 lb CO2 tank last"? question I've been asked several times. Using most restrictive use methods in a closed 4x4 tent:
* Electronic regulator connected to a CO2 monitor that limits to 1500 PPM with auto turn off at night
* During Veg, run CO2 continuously the 18 hr lights on cycle CO2 turns off when it hits 1500ppm, then kicks back in when needed); only vent tent when lights off (when Co2 is auto shutoff); downside became humidity buildup happening, hard to control. I felt the gamble was OK without budding and 2 tent pole fans and 1 on the floor moving air. CO2 is a heavy gas that likes to sit at the bottom of the tent.
* During flower, running 30 min on CO2 with no exhaust fans; running 5 minute exhaust cycle (with CO2 off) to lower humidity, then repeating that cycle continuously during the 12 hour lights on

Doing all that, a full 20 lb tank lasted me 107 days. IMO I think the investment in the regulator and monitor (appx $300 US) paid for itself in a single grow (versus not having those) as I have heard a tank lasting appx 10 days using flow rate to space determination and larger space or tents.....for me a tank refill using my own tank is $29...PLUS, and this is very important, you should not run CO2 with lights out, you will kill your plants.

I love CO2, it's a gas!
Ok so I have a regulator electronic monitor with photocell for night time shutoff I dont vent my tent at all only the light gets vented I have the scrubber up at the top with a duct around the top pointed back at the scrubber dehumidifier inside the tent air conditioner outside with ducting running under the table to blow any co2 from underneath 2 pole fans kitty corner flow meter set at .5 ppm set at 1500. Am I leaking that much gas? I even taped all the zippers and seams just in case also taped my fixture. Mind you I only veg for just over 2 weeks I get aggresive growth 2" a day. But still running out with tanks every 3 weeks at $60 a pop plus gas plus time. Everything I read said I should get about 10 days in my enviroment which is a 4.5 ×4.5×84 so how you get 107 days blows me away.
 
Ok so I have a regulator electronic monitor with photocell for night time shutoff I dont vent my tent at all only the light gets vented I have the scrubber up at the top with a duct around the top pointed back at the scrubber dehumidifier inside the tent air conditioner outside with ducting running under the table to blow any co2 from underneath 2 pole fans kitty corner flow meter set at .5 ppm set at 1500. Am I leaking that much gas? I even taped all the zippers and seams just in case also taped my fixture. Mind you I only veg for just over 2 weeks I get aggresive growth 2" a day. But still running out with tanks every 3 weeks at $60 a pop plus gas plus time. Everything I read said I should get about 10 days in my enviroment which is a 4.5 ×4.5×84 so how you get 107 days blows me away.

Is your monitor set to stop the flow when you hit 1500 ppm? I've got 3 lights on my monitor...1000ppm, 1250ppm, 1500ppm...I can literally "see" the tent fill with CO2 by watching the lights. I can hear the monitor shut off the solenoid on the regulator when that 1500ppm light comes on. Sounds like to me that type of regulation might not not happening in your situation? Additionally, my lights are not vented, they are LED and have internal fans inside their case that blow out of the fixture but it all stays in tent. Do you push or pull air into the light vent? If you push air from outside the tent, I would think you might run into a situation where your tent bloats up and Co2 saturation never quite happens. If you pull air from the light vent, I could see how it might be possible to pull some CO2 out.If it were me, I'd rather pull air from the vent as you can always seal up the light like you have and have better CO2 control overall.

I'll tell you the dynamics of something I noticed in my own setup. If someone in my house runs a bathroom vent or a stove vent or the dryer runs on the 2nd or 1st floor of the house, it will pull the CO2 (and the MJ smell) right out of my sealed tent in the basement. The smell then makes its way up the furnace vents to the first floor. I'm like you, I have every possible exit of my tent taped up best I can. Even outside doors opening on the 1st floor will cause negative pressure for a moment in a sealed home. My point is, if you are leaking CO2 from the tent, you should smell the MJ too. The stronger the smell, the more leaking probably happening. When my in/out vent fans run for 12 hours during sleep, I get zero smell, as I should.
 
Hey USA, can i ask how many ladies are in your space that your feeding with co2? I do 9 at a time. Also I get 0 negative pressure in my tent, cant smell anything unless a/c is balloning my tent. So I assume there is a small leak somewhere, pretty sure I know where it is but cant fix due to balloning, had to cut through mesh to accommodate flood and drain lines, taped them up but not working well. Just got rid of my 1000w a/c fixture and replaced with 630 cmh. So no more venting the lights, hopefully that helps. Also gonna try plugging co2 monitor/controller into my environmental controller, to stop a/c and dehumidifier while enriching, cant see how it'll help being a sealed space there should be nowhere for the gas to go but be absorbed.
 
Hey madframermrc, I have 4 ladies in my 4x4 and collectively they take up the entire tent. I vegged for 9 weeks and FIM'd each top only once, and LST'd them to create wide plants.
regarding smell, I have a gorilla tent. I can tell you what I found happening to mine probably happens to most - I found I had leaks at the front zipper where points meet up and they have overlapping flaps that block light at the intersection points but not the smell. (the up and down zipper) What I did to fix this was fold up a paper towel into a 2 inch by 2 inch and stuffed it into that area and then zipped the zippers against it on those 3 sides.

Sounds to me like you got the venting issue dialed in now. Be aware, but comforted, knowing that with CO2 you can run higher temps and humidity - mid to high 80's for both are OK, so long as you vent (or in your case, a/c) during 12 hr sleep period to bring overall humidity down. During the day, the plants take the CO2 in and produce oxygen in its place. So I notice from time to time (watching my monitor lights) the Co2 level in the tent drops, a little more gets released, etc. A real sealed tent with my LED lights to produce mild heat, with 3 fans running....the humidity build up. You have to vent it, or run A/C. I found that every 30 minutes, I have to vent during lights on, to control humidity. Thats why I need separate timers for my fans, and my lights, and my co2.

Heres my schedule.
During lights on period:When my fans run, my CO2 does not, and vice versa.
When lights are out, my monitor has a feature that shuts off CO2. My fans run full 12 hrs.

CO2 FAN LIGHTS
10 10:35 10:35 10:40 10am 10pm
10:40 11:15 11:15 11:20
11:20 11:55 11:55 12:00
12:00 12:35 12:35 12:40
12:40 13:15 13:15 13:20
13:20 1:55 1:55 2:00
2:00 2:35 2:35 2:40
2:40 3:15 3:15 3:20
3:20 3:55 3:55 4:00
4:00 4:35 4:35 4:40
4:40 5:15 5:15 5:20
5:20 5:55 5:55 6:00
6:00 6:35 6:35 6:40
6:40 7:15 7:15 7:20
7:20 7:55 7:55 8:00
8:00 8:35 8:35 8:40
8:40 9:15 9:15 9:20
9:20 9:55 9:55pm 10am
 
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