Myth busters - the real truth on CO2 in indoor grows

[legalizeitcanada]

So i gotta question, im growin in a fridge, I wanted to do a closed system for the flowering chamber, would putting in a yeast based Co2 system with air pump work to bring enough fresh Co2 for the plants to breathe between door openings, there would still be an internal fan to move air, but the chamber would be sealed, only the light would be vented using a cool tube.....think this would work????

Experiment 1 for generating co2 from yeast/sugar: used homebrewer's ratio of sugar to water and XxNinjaxX's amount of yeast (see Sticky: HomeMade CO2 Guide), at least for this first attempt.

Room details - 384 cubic feet, closed really tight (takes effort to open the door due to negative pressure when exhausting, which i've stopped for this experiment), a/c, 600 watt mh light, 170 cfm fan pulling carbon filter and recirculating air, 15 two to three week old seedlings.

household co2 equal to 650 ppm.

Formula: 2.25 gallons of water/3.1 pounds sugar/46 grams of yeast in 4 separate containers. i cheated and ran one liter bottle, saw how much my co2 jumped, and scaled it up to target 1,500 ppm co2.

Ended up with 1525 ppm at 11 pm on 6/27/10 after running two hours.

co2 at 1625 at 3 pm on 6/28.

co2 at 1575 at 5 pm on 6/28/10.

 

[desertrat]

So i gotta question, im growin in a fridge, I wanted to do a closed system for the flowering chamber, would putting in a yeast based Co2 system with air pump work to bring enough fresh Co2 for the plants to breathe between door openings. think this would work????

your biggest problem would be keeping co2 from spiking up over time. you'd have to get the amount of ingredients just right to produce at the same rate the plants use it. or, you could just poke a small hole in the fridge. in a typical household grow room you get something like an air exchange every two hours without doing any venting just from air moving through micro cracks in construction, bringing the co2 concentration back toward the amount in the rest of your house (actually trying to nail down that number during this experiment, at least for my room). you get no air exchanges except when you open the door so if co2 is added faster than the plants use it you're in trouble. all said and done, best to have a couple of small holes. like with a 1/8 inch drill ought to do it.

 

[legalizeitcanada]

kewl thanks for the input man.....appreciated!

 

[eps]

I am loving this experiment. Keep us updated!

 

[mydixiewrecked]

hate to throw a wrench into your experiment, but running a activated CARBON filter will increase your c02 level.
http://en.wikipedia.org/wiki/Activated_carbon

 

[desertrat]

hate to throw a wrench into your experiment, but running a activated CARBON filter will increase your c02 level.
http://en.wikipedia.org/wiki/Activated_carbon

very, very big sigh. i'm trying not to be rude, but it's kinda silly for you to be telling a research and development chemical engineer your opinions from misreading wikipedia. the activated carbon in a carbon filter is a solid and never, never becomes suspended in air much less chemically altered to co2. the carbon in the filter bonds with aromatic carbon compounds (ie smells) and pulls them from the air, not the other way around. the carbon never leaves the filter. members on this site try very hard to be fact based, welcome to our family but please spare the uniformed opinions unless you label them that way.

 

[desertrat]

on to new business, co2 at 1125 just now so the sugar/yeast solution has kept the grow room between 1025 and 1625 ppm for two and a half days, the minimum time i was shooting for with this first experiment.

i'm planning out the second experiment based on these results. from here it appears that a ghetto yeast/sugar mix does provide meaningful, controllable and predictable amounts of co2. the biggest problem i see for general use is that the co2 requirements of plants and the amount of co2 that leaks out of a room are different for each grower/grow and if the differences are significant then there is not a single answer for a grow room of a given size.

 

[zer0ed]

i love all this information. keep up the good work.

I would love to run a simular experiment someday. maybe if its just to supplement a co2 system. (or maybe the other way around, the co2 tank will just top off the room at 1,500ppm) to use much less tank co2.

+rep

 

[desertrat]

well, hit me over the head with a 2 x 4. this was simple. for the second experiment i'm going to run the ghetto system in my flowering room this time and see how much of a difference is made by a more leaky room and more plants. i'll start it as soon as the first experiment falls below 1,000 ppm permanently. i'll scale the ingredients down to fit the smaller room but keep the ingredients the same. then the only reason for readings different from the first experiment will be because of the tightness of the room and the number of plants. at least we can nail down those two variables taken together. against my prior judgement, i really think this ghetto system has a chance of working as well as an expensive co2 system. who'd of thought it?

 

[mydixiewrecked]

I owe you an apology,I am a total noob, but your reply helped me solve a problem, my monitor was reading extremely high levels, I justed turned on my filters,which are new, so I thought it was the cause, after reading your post, I checked things out and found my regulator leaking.

 

[desertrat]

i love all this information. keep up the good work.

I would love to run a simular experiment someday. maybe if its just to supplement a co2 system. (or maybe the other way around, the co2 tank will just top off the room at 1,500ppm) to use much less tank co2.

+rep

thanks. if this works, there's no reason it won't work without any other source of co2. you just have to get the ingredients right and probably add one new bottle a day and take out one old bottle, keeping each container in the room for two days (or longer if you use larger containers). that will take care of the tendency for the ppm to rise early in the cycle and then decline, the various curves from multiple bottles would overlap giving you a pretty steady stream of co2. i'll try to nail that down after i've taken care of variations in room tightness and plants.

 

[Nitegazer]

Subed-- I love actual experimentation. This ought to be good.

I have considered yeast based CO2 for my grows, but am concerned that nutes, temperature, et. al. have to be so optimized before any benefit is realized. I figure I could get much better gains by just bumping up the lumens a bit or something else just as easy. I look forward to finding out how much effort must be applied to realize a gain in yeild. +rep

 

[desertrat]

I owe you an apology,I am a total noob, but your reply helped me solve a problem, my monitor was reading extremely high levels, I justed turned on my filters,which are new, so I thought it was the cause, after reading your post, I checked things out and found my regulator leaking.

apology accepted, sorry i was a bit of a dick.

 

[mydixiewrecked]

no worries

 

[desertrat]

well, the fermentation reaction finally petered out below 1,000 ppm co2 this afternoon. it lasted 2 1/2 days which was at the low end of my estimated run time. it appeared there was still sugar left in the mixture, so it probably ended because there was too much yeast resulting in high levels of alcohol being produced (i find it really ironic that i'm making drinking alcohol as a by-product of growing weed).

 

[desertrat]

Second experiment - I'm using the same ratio of ingredients scaled down for my smaller flowering room. The purpose of this experiment is to test the impact on co2 of a leakier room and larger plants. Mix is 1.6 gallons water/2.2 pound sugar/32 grams yeast ( probably way too much).

Third experiment- I'm keeping everything the same as the first experiment in my veg room but lowering the amount of yeast. Mix is 2.25 gallons water/3.1 pounds sugar/12 grams yeast.

I'll post updates.



Edit update- these experiments cratered when they failed to start sufficient fermentation, I believe because the water wasn't hot enough to fully activate the yeast ( I think the jar called for 114 f warter). So I bailed on the fancy tests, put all of the bottles in the veg room and am just going to keep track of the time this stays above 1000 ppm.

 

[desertrat]

Just gotta say, doing these experiments is a real pain. Either I have to hold my breath when I go into the rooms or I have to vent the room bAck down to my pre- visit level. And i for one get a lot of pleasure out of tending to my plants. I might take just as much care for a non medicinal plant...naaaa

 

[Murfy]

some ave suggested that simply being in the room provides a rather high concentration of co2 from respiration-

how big is your room, and how much does your breath raise the ppm in one minute? if you are so inclined.

 

[homebrewer]

Nice experiment! It's no question that fermentation produces CO2, my argument was; is it worth the time, effort and cost? Subbed for your results.

 

[desertrat]

some ave suggested that simply being in the room provides a rather high concentration of co2 from respiration-

how big is your room, and how much does your breath raise the ppm in one minute? if you are so inclined.

under my best med right now, so maybe off and I'll revisit and edit if needed, but I want to say about 50 ppm a minute in a 384 cubic ft room.

Edit - it takes 2 minutes to increase by 50 ppm in my 384 cubic ft room, so 25 ppm per minute.