Myth busters - the real truth on CO2 in indoor grows

moash

New Member
My first time trying it, but the sludge at the bottom is supposed to be full of active yeast cells, I dumped out 90% of the liquid and added new water and sugar.

:-?
uh oh,the face:-?
haha, let me know how the recycled yeast works
 

Murfy

Well-Known Member
are you stopping the co2 flow during lights out, or are these free flowing? if you do plug the container what does the reaction do? stop? when it gets to a certain pressure?
 

The Potologist

Active Member
There seems to be a lot of misinformation about how much co2 (carbon dioxide) is available to indoor plants, and how to think about whether and how much co2 to add if you decide to enhance co2. I took my calibrated co2 meter on a hunt for the truth.

As an aside for newbies, don't confuse carbon dioxide (CO2) that your plant uses with carbon monoxide (CO) which is a poisonous by-product of burning fossil fuels.

First myth - you should add CO2 indoors because there is less co2 in a closed indoor environment than what an outdoor plant gets. This is just not true. A normal indoor situation of an inhabited structure with central heating/cooling has as much as twice the amount of co2 indoors compared to outdoors. You do not have to add co2 to equal outdoor conditions. For example, in my case the outdoor co2 is at 400 ppm (national average is 390 ppm, thank you climate change) and indoors it's 650 ppm.

Second myth - adding co2 will improve your grow. This is only true under special conditions. The reason experienced growers add co2 is that if all other environmental conditions are optimized (water, nutes, light, temperature, humidity, medium, container, ph, insects, etc.) then and only then will increased levels of co2 (typical target is 1,500 parts per million) be used by cannabis plants to grow faster. Adding co2 without dialing in your grow will not change anything. if you are just starting out then don't worry about co2 for your first few grows.

Third myth - a couple of plants in a closed closet will exhaust available co2, requiring action on the grower's part to compensate by (a) actively ventilating to bring in fresh air or (b) by adding co2. In the vast majority of cases this is not true either. Home construction of internal walls is just not that airtight. An easy experiment to test your grow room - close off any inputs you've created and turn on the exhaust - the fan will run and air will continue to be forced out of the room indefinitely. If you have a tight room you can lower the air pressure (ie create negative pressure) but you won't be able to pull a vacuum because air will leak into the room from thousands of tiny cracks. The rule of thumb for an un-vented room is a complete air exchange every two hours. That new air will have more co2 than outdoors. In addition, the higher partial pressure of co2 outside your grow room will cause co2 to migrate into your room faster than other components of air. I have checked repeatedly and the co2 concentrations in my grow room are always within 100 ppm of the rest of the house, and considerably higher than outdoors, even without noticeable negative pressure and with a closet full of plants. Unless you're growing in a refrigerator or tent or similar (or you are growing dozens of plants) you don't have to do anything to get enough co2 for your plants.

Fourth myth - carbon filters emit co2. no, they don't. Carbon filters remove smelly compounds from the air, they have nothing to do with carbon dioxide. Thanks to mydixiecrat for helping to point this out.

Fifth myth - you need expensive co2 generating and monitoring equipment to maintain the proper levels of co2 if you choose to enhance. Okay, I bought into this myth and I believed it enough to get a $400 co2 monitor and a $450 gas generator. So, I thought I'd get a little extra back from my investment. I have the gas generator running in my flowering room but nothing for my veg room. I'm going to use my monitor from the flowering room to test whether it's really possible to build a ghetto sugar/yeast co2 system that produces a steady and predictable concentration of co2. I'll keep updating this thread with results - maybe the next person can save the $850 plus propane costs with a couple of kitchen supplies. Results so far show that a sugar/yeast system is quite good at providing a relatively steady, predictable and meaningful amount of carbon dioxide.

:-?
AMEN!! I found the same thing to be very true. I measured Co2 all over my house, took it for a two mile walk, and then came by indoors. Nowhere outdoors did the Co2 compare to the levels indoors. The highest I found, sadly, was near a school, which came in at 441ppm. Indoors, the lower end of the spectrum still came in at 650. Down in my basement I reached levels as high as 900ppm.

Also, I only turn on my Co2 generators when the conditions are perfect. Otherwise its just a utter waste. I have done a great deal of testing and found that unless your temps are AT LEAST 87F, Co2 consumption is not going to increase. Moreso, I noticed that as my temps rise in my indoor grows, so does Co2ppm....weird eh? However, once my temps do reach at least 87F I turn on Co2 and the growth is really rampant. Typically it will also aid in elevating the temps as well.

Just my two cents. Hope I was some help to someone. BTW, Co2 generators are stupidly expensive. Luckly, I have a great construction connect and picked up four of them for about the same price of one...But I still say it was a bad investment, especially considering I never gave a single thought to fabricate my own homemade Co2.
Peace, Love and Happiness
 

moash

New Member
AMEN!! I found the same thing to be very true. I measured Co2 all over my house, took it for a two mile walk, and then came by indoors. Nowhere outdoors did the Co2 compare to the levels indoors. The highest I found, sadly, was near a school, which came in at 441ppm. Indoors, the lower end of the spectrum still came in at 650. Down in my basement I reached levels as high as 900ppm.

Also, I only turn on my Co2 generators when the conditions are perfect. Otherwise its just a utter waste. I have done a great deal of testing and found that unless your temps are AT LEAST 87F, Co2 consumption is not going to increase. Moreso, I noticed that as my temps rise in my indoor grows, so does Co2ppm....weird eh? However, once my temps do reach at least 87F I turn on Co2 and the growth is really rampant. Typically it will also aid in elevating the temps as well.

Just my two cents. Hope I was some help to someone. BTW, Co2 generators are stupidly expensive. Luckly, I have a great construction connect and picked up four of them for about the same price of one...But I still say it was a bad investment, especially considering I never gave a single thought to fabricate my own homemade Co2.
Peace, Love and Happiness
do u mean at least 87 or higher
or at least 87 and lower
edit:nevermind dumb question
 

desertrat

Well-Known Member
are you stopping the co2 flow during lights out, or are these free flowing? if you do plug the container what does the reaction do? stop? when it gets to a certain pressure?
no way to stop the reaction So this is one of the ways the fermentation reaction is less efficient than other methods.
 

desertrat

Well-Known Member
The co2 level was haNging around 1100 Ppm so I added About 20 gramS of bakers' Yeast to boost the reaction. Co2 at 1525 ppm at 10 pm.
 

moash

New Member
The 2 level was haNging around 1100 Ppm so I added About 20 gramS of bakers' Yeast to boost the reaction. Co2 at 1525 ppm at 10 pm.
do u think its possible to have a big container with the ingredients,and when it runs down ,just keep adding sugar and yeast....so u dont have to keep switching containers around
 

mydixiewrecked

New Member
here is a experiment, or maybe someone has tried it, put a flowering plant in a 100% sealed room, turn on the lights and have 1500 ppm
set inside, watch the plant and levels from the time the lights come on.
never giving the plant fresh air, only c02
do the same thing with a plant, just using fresh air exchanges.it would be a tough experiment, but the outcome would be very interesting.
 

desertrat

Well-Known Member
do u think its possible to have a big container with the ingredients,and when it runs down ,just adding sugar and yeast....so u dont have to keep switching containers around
the fermentation seems to last about three days max, no matter the size of the batch. You'd have to ask homebrewer why, but I think the yeast multiply until there are enough cells to finish the reaction. Look back a couple of posts and he suggests a big batch and submerging the container in cold water. Going to try that later.

here is a experiment, or maybe someone has tried it, put a flowering plant in a 100% sealed room, turn on the lights and have 1500 ppm
set inside, watch the plant and levels from the time the lights come on.
never giving the plant fresh air, only c02
do the same thing with a plant, just using fresh air exchanges.it would be a tough experiment, but the outcome would be very interesting.
this is exactly what growers who use co2 do, within the practical limits of sealing a room. A the co2 enhanced plant will grow faster if it has all of it's other needs met.
 

desertrat

Well-Known Member
Co2 was at 1325 ppm at 8 am when I subbed out one two day old container with a brand new one. Now using .9 gallons water/1.25 pounds sugar/15 grams yeast.

:-?
 

mydixiewrecked

New Member
the fermentation seems to last about three days max, no matter the size of the batch. You'd have to ask homebrewer why, but I think the yeast multiply until there are enough cells to finish the reaction. Look back a couple of posts and he suggests a big batch and submerging the container in cold water. Going to try that later.

this is exactly what growers who use co2 do, within the practical limits of sealing a room. A the co2 enhanced plant will grow faster if it has all of it's other needs met.
that's the way I do it, I figure the earth is only inhabitibatal because plants and trees where able to bring c02 levels down enough for humans to have enough oxygen. Bringing fresh air in invites mold spoures and bugs access to your girls.
 

desertrat

Well-Known Member
do you notice the levels drop after lights come on?
No. It seems the passive exchange of air in and out of the room has a much bigger effect on co2 levels compared to the effect of the plants. Somebody estimated plants take in 100 ppm of co2 per hour while the room loses something like 500 ppm of co2 per hour to passive leaks, but I haven't seen proof.

:-?
 

desertrat

Well-Known Member
Co2 at 1400 ppm at 5 pm. Looks like rotating containers is a practical way to maintain a high level of co2. Going to give it another day or so, then I'll write up the formula and steps needed to make it work.

:-?
 

moash

New Member
Co2 at 1400 ppm at 5 pm. Looks like rotating containers is a practical way to maintain a high level of co2. Going to give it another day or so, then I'll write up the formula and steps needed to make it work.
:-?
looking forward to it
 
1225 ppm at 7 pm, 50 hours above 1000 ppm. Looks like 2 1/2 days may be the limit. Any ideas on how to extend the time? Homebrewer or ninja??
I have made beer and mead. The mead is made with honey and ferments for about 8 weeks at a slow pace. The beer is made with sugars rinsed off cooked(155 degrees F) grains. Simple sugars seem to ferment faster. Adding more yeast will start my fermentation faster and be more robust. A five gallon container of wort with 15 grams of brewers yeast will use up the sugars in five days tops. Doubling the yeast and it is finished in three days.
 

desertrat

Well-Known Member
I have made beer and mead. The mead is made with honey and ferments for about 8 weeks at a slow pace. The beer is made with sugars rinsed off cooked(155 degrees F) grains. Simple sugars seem to ferment faster. Adding more yeast will start my fermentation faster and be more robust. A five gallon container of wort with 15 grams of brewers yeast will use up the sugars in five days tops. Doubling the yeast and it is finished in three days.
I am really going to have to start charging for experiments but using a complex sugar is a thought worth trying out.
 

homebrewer

Well-Known Member
Parishollow is correct in that disaccharides take longer to ferment than monosaccharides. The catch is that disaccharides (honey, or a maltose) is MUCH more expensive than simple table sugar. When beer is made correctly and when the proper amount of yeast is pitched, you wont see more than 5-7 days of fermentation. Mead usually ferments longer because there is very little food for the yeast to use in order to ferment out the honey. That's why a lot of mead makers subscribe to the 'staggered nutrient additions' method and in doing so, will produce a good product in about 3-4 weeks. Again, 15 lbs of honey or 15 pounds of malt extract/grain isn't cheap and considering an 8 week grow could need refreshed with a new 'batch' every 5-7 days, that gets down right expensive.

A monosaccharide like sucrose is easy for yeast to ferment, so in addition to changing the fermentation temperature, you could also cut your pitching rate in half (use less yeast) to see if that helps extend your ferment.
 
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