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Co2 bag’s, yay or nay?

I got a myco2 bloom bag, I got the bag on the floor away from the exhaust vent I was going to keep the tent closed up and shut off the exhaust but it got hot rather quickly! So I turned the exhaust back on.

My question is will the c02 bag be effective at the bottom with the vent on or is it just a waste of time, my room is probably 15×10 I figured the exhausted co2 may circulate back in the tent?


13 responses to “Co2 bag’s, yay or nay?”

  1. 413indoorgrow Avatar

    I’m curious about the real science behind these c02 bags. I’m running one c02 bag I got off amazon in my 4×4 tent. I dont have a reader at the moment and can not run bottle cow in my appartment. I’m hoping they do put out c02 just unsure of the amount, I’ve heard 500ppm per bag but tottal bro science. Following this thread

    1. keikeoki Avatar

      Do the math, man!

      The “real” science is actually simple. Beyond getting a co2 meter to actually measure what you have before, during and after you introduce your source, you can easily get an idea of what is possible… Co2 has mass. Your co2 bag also has mass. Some of the mass of the bag is the bag, and the water in the medium. Some of the mass of the bag is the food source for the fungus to grow. 100% of the co2 produce com3es from the limited amount of carbon in the fungus food inside the bag. You can never produce more co2 than you have carbon in the food. Fun fact, wood is about 50% carbon by weight. 14/32 of co2 is carbon (43%). You won’t likely release all of the carbon, so let’s assume you release 80% of it… so 40% of the weight of the DRY wood mass is available carbon, and ~40% of the co2 is carbon… So the ROUGH measure of the co2 produced will be very close to the dry weight of the wood provided for food.

      Make your own mushroom grow bag, and before you wet the medium, weigh it. That dry weight will be close to the maximum co2 it is capable of producing in THEORY only. In practice as little as 50% of the food will be consumed, reducing the co2 out by the same 50%. How tight you pack your bag will limit the mass of course.

      So I did not weigh my bags, and my bale of wood chips I use is measured by volume not mass, so I can only guess… One user of straw based grow bags states they use around 2 pounds of straw, and the rest is water… so let’s be optimistic and say we will use 5 pounds of wood shavings/sawdust/pellets. If we get half of that back as co2 mass, that means my bag will produce 2.5 pounds of co2 over it’s lifespan. It could be a little more, it could be a lot less. It will never be more than 5 pounds.

      In a small grow room you might make a 20 pound cylinder last 40 days for a given target concentration. 40 days is around a third of the lifespan of a bag, so 1/3rd of 2.5 is .825. Divided into the mass provided by a 20lb cylinder, I see it would take 24 bags to put out as much co2 in the 40 day period.

      I use a lot of round numbers and guesses here, but I am at least close to the stoichiometric actuals. Laws of physics being what they are. But the point is clear, you CAN use mushroom bags for your co2 supplementation. But do you want 2 mushroom bags for every 1 plant??

      The reality is when you read the claims of the bag sellers they never give you an actual measurement. On one page I read 1500ppm can be produced by a bag, another page states 1000 ppm. I’m sorry by ppm is not a measure of mass, it is a concentration only. It actually is a nonsensical statement without a LOT more numbers. What size of space, how much time does this take? Is it faster or slower than “x” pounds of leaves transpiring under how much light? My point is if they give you a ppm number, it has no meaning without all of the other numbers that contribute to the final concentration.

      But if you are comparing it to a tank of co2, pound for pound is the only meaningful measure. And while I only guessed at the specific numbers, I did not wildly speculate. I used chemistry concepts and the law of conservation of mass.

      So yeah, roughly 24 bags will produce as much as 3 20 pound tanks total, but at a rate of 1 tank every 40 days. Do your own math, but if you are growing in a tent, how much of your tent needs to be filled with mushroom bags? Probably more than you were thinking.

    2. keikeoki Avatar

      oh, in my long post, I made a math error… 27% of co2 mass is carbon, not 43%… oops! So the number of bags required is reduced a bit. So instead of 24 bags, it might only be 15 bags.

      My original premise is intact, though the severity of the problem is reduced.

      I should add if you burn the wood instead of grow mushrooms in it, you get more co2 much faster… but now you have to scrub out the soot and other contaminants.

      I think co2 tanks OR high-volume air exchange are the correct and best answers.

  2. Not_a_meme_Guy Avatar

    I use one too. Havent bought the meter, but I use it primarily as a humidifier I don’t have to refill.
    You did it right according to the directions, but I don’t notice any difference and I use it without exhausting the tent.

    The Dude put a bag and his meter in some kind of small enclosure…a tote or something…he got I think 1000ppm reading. Anyway it was a very small space and it just shows the bags do produce c02, but you’ll probably have to hang about 6 of them or more in a 4×4 to notice a benefit.

    Works great as a humidifier once activated though!!

  3. SpartanGrown Avatar

    The bags are based on the fact that mushrooms (fungus), like us, breathe in oxygen and breathe out CO2. Fun Fact, that is one of the reasons Paul Stamets thinks we may be descendants of fungus. In the bag is some food and some mycelium (the mushroom veg phase). The exhale bags have the two separated and you combine the two to “activate” it. This is why those bags take a month to start working, because the fungus is just trying to get started on eating before it starts farting out that sweat CO2. As the mycelium breaks down it’s giant block of food, it grows and spreads and starts to put out it’s peak CO2 until it runs out of food at around the 5 to 6 month mark. The bag keeps the mycelium from fruiting (growing mushrooms) but if you cut a hole in the bag, mushrooms will pop out (just make sure you harvest them before they jizz spores all over your room).

    I have tried the exhale bags and wasn’t too impressed, but then I tried a local product called Deez Bagz and those worked great. I hung 2 bags over each 4 x 4 and it was keeping me around 800 ppm average and they lasted about the same 5 months, but come already started, so they got going faster. They also had a variety of blue oyster mushrooms so you can cut your holes and grow out some edible mushrooms if you like.

    All that said, I have since gone to using bottled CO2 because it is so damn cheap after you pay for the tank and regulator. To answer your direct question though, You already bought it, it costs you nothing to keep it in there, keep it in there. It will hurt nothing, and for sure add at least SOME kind of benefit, even if it is just a passing wiff of pure CO2..

  4. Not_a_meme_Guy Avatar

    So the science is the michrooms spores fart out co2 🙃

  5. SpartanGrown Avatar

    LOL No, sorry high SpartanGrown makes bad jokes. The fungi exhales the CO2 and breathes Oxygen.

  6. highhog_og


  7. Johnychimpo Avatar

    Do you think the co2 would be re circulated back in the tent? Its a 4×4 tent, but the room is a closed 15×10 that’s what I meant to put in the question, and thanks for all the info .

  8. 5150shredder Avatar

    Get a Co2 Monitor so you know your ppm. My understanding is if you have to vent your tent because it gets to hot, put your Co2 bag on the floor at your intake and exhaust out the top-opposite side of your tent. That way the Co2 is being pulled up threw the canopy allowing your plants to use it. If you dont have a controller Maybe put your exhaust on a timer. So it can turn off briefly and build Co2 back up. On a side note get your VPD on point so you know for sure your plants are using up all it can in Co2, water and nutrient uptake and perspiration. What this does is open up the stomata wide open to breath like a highly tuned race car giving your plant’s the optimal environment to perform. Download a VPD chart or get a Pulse monitor keep that VPD dialed in and your tent should explode!!!👍🌿💯😎💚🔥Temperature+Humidity=Vapor Pressure Deficit (VPD)

  9. Not_a_meme_Guy Avatar

    If the room is sealed your plants will use all the co2 in the room then youll have problems, if not then all the co2 in the room will recirculate into the tent, but the co2 bag wont give you any more co2 than what is slready present in the room. Maybe 1 ppm more? lol

  10. Not_a_meme_Guy Avatar

    To clarify, the small amount of co2 that bag releases will be less concentrated when mixed with more air and the room size is too big to be see a measurable difference. You’ll be ok exhausting the tent with the bag on the floor by the passive inlet, just don’t expect increased performance. Just be content that you wont be depriving your plants of co2. (I take back my comment about the problems if your room is sealed…that’s a whole other topic and When you enter that room daily you’re adding co2 to that room anyway).

    If you aren’t exhausting constantly or if there is a long enough gap between fan cycles, I would put that bag above your plants and maintain good airflow above and beneath the canopy with small fans.

  11. AZKushman Avatar

    Gotta disagree some not on the bags…did not like them much but just finished run with co2 yeast reactor per lady…big difference….open room now out from the 4x8x7 tent I went with a 20# tank….dozen now so not practical to do reactor per anymore but I was very happy with what I got last grow and 4 to6 oz dried per lady. ..did a 2 stage harvest over a week,cut primaries then let lowers fatten….,measured 700to 800 ppm at this stage at one point…and buds were dense and sticky…but as Spartan and I have discussed a tank is just so much easier,especially if on a 6+ lady grow….I also got some brewers yeast at one point and it produced alot of bubles… 91 in a minute we counted stoned lol…I found that on start up less sugar initially allowed to yeast colony to live longer had one reactor last 5 weeks….1/4 cup of sugar a day….I also had a 6″ exhaust fan running dialed down on speed control to minimum shut down at night….now my reactors contrary to Co2 advice were producing Co2 24/7 so upon wake up ladies had a bunch built up over the night…..I achieved 25% greater yield this time as well. I think my total cost for a 4 week veg and 8 week flower was under $40

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