Diving into C02.. here we go

Good afternoon RIU! Today i wanted to touch the topic of supplementing C02, ive been growing for nearly a decade now, have tried a little bit of everything when it comes to growing, but ive never had a need to supplement c02 for my grows before. Let me give you the back story of why im getting into it now:

Im getting ready to move in just under 2 months due to my lease being up, and i already have the place im moving into picked out, the only snag i've run into though is that my new place has no where for me to intake fresh air from! The place im moving into is a condo and only has a single window in the unit that is front facing, on the first floor, and is the first unit in the row of units, so i just cant feel safe pulling intake from it as hundreds of people will walk by it daily, even if i built it as discreet as possible it will be noticed by someone, again my unit is the first one in the row of condo's so literally everyone that lives there has to walk by to get to their own units. Even if i was 1000% sure that no one would notice it on their daily walk by, theres a rather zealous HOA that manages the place and they dont allow "window modifications".. cant have window a/c units or flower pots on the window sill, you cant even have curtains showing from the outside, only blinds, or they will fine you- my grandparents own the condo next door to the one im moving into for anyone who's curious how i know these rules already before actually moving into the place.

So since i cant draw fresh air in from outside im going to have to supplement c02 for my garden. Now the good news is i have already started researching this a bit and have discovered that those bags you can buy and hang in your tent for c02 are nothing more than a bag of substrate colonized by mycelium, now you may recall where i said my grandparents own the condo next door to the one im moving into, my grandparents own it but my cousin lives in it, and my cousin happens to be a cultivator of everyones favorite kind of mushrooms so he has a nearly endless supply of mycelium that i have access to so i dont have to purchase it.

Im still doing my research but one thing i had read online was that you dont want to release c02 during lights out because the plants cant use it during that time, but a trusted friend whos been growing for close to 3 decades has told me that its perfectly fine to still have the c02 bag in there during lights out and that the plants just simply wont use it during that time and that it wont harm them. so im really just making this thread hoping to hear from some others that have experience with this stuff because some of the articles ive read make it seem like releasing c02 during lights out is actually harmful (and yes im aware that too high levels of c02 are harmful but im referring to levels between 600-1500ppm) but my friend tells me that people just make it seem that way because they're high-strung about not wasting their precious c02 that they pay for, but again i have a nearly endless supply of mycelium so im not worried about the waste factor.

Typically, those CO2 bags are junk and will barely raise your CO2 levels. If your grow room is sealed enough, just you simply being in the grow room and breathing will increase your CO2 ppms by around 100-150ppms. When my propane tank is empty, ambient CO2 is usually between 350-400ppms. However after being in the grow room for 15-20 minutes the ppm rises to around 450-500ppm.

If you're going to run CO2, a propane/natural gas generator or a tank+regulator is really the only way to go. I never liked the idea of tanks because; 1) finding a place to refill a CO2 tank can be a bitch, and 2) even if you CAN find a place to refill said CO2 tank, it isn't exactly very discreet to refill a 50lb tank every 2 weeks unless you happen to own a business that uses CO2 tanks (e.g. fountain drinks, kegs, etc).

Propane is cheap as shit, lasts a decent amount of time, and no one will ever second guess someone refilling propane tanks 1-2 times a month. Only downside is you'll be spending ~$250 on a CO2 generator and another $200 for the controller (which is pretty much a mandatory purchase). However, the results will allow you to get your money back and then some. I had to run CO2 for the same reasons you do. I need absolute discretion and absolutely cannot have an intake/exhaust for my room, so the only other option was to have a completely 100% sealed room that is supplemented with CO2.

Now, you can get away with supplementing to ~400ppm or so to compensate for the fact that you will have zero fresh air coming in and call it a day no problem. However, if you're going to spend the money you may as well make the most of it and supplement to 1000-1500ppm.

Just a few things to consider should you decide to go above 400-500ppms.

1) More CO2 means you will need more light, nutrients, and water. As I'm sure you already know, plants uptake CO2+light+water/nutes and exude sugar + O2. So, if you increase the CO2, you'll also have to increase the other variables in the equation, otherwise the extra CO2 will literally be useless as the plants will be unable to process the excess CO2 without an excess amount of light, water, and nutrients as well. K and Mg are directly responsible for photosynthesis, and as a result, when supplementing with CO2, you will likely notice K/Mg deficiencies before anything else. I had the pleasure of finding this one out the hard way. Simply make a foliar feed of Epsom Salts (Mg) and Pro-Tekt (Silica+K) and you will be fine.

2) In most cases, going above 700-800ppm will be absolutely useless/superfluous unless you have 1000w+ in lights. You'll also want your temps to hover anywhere between 78-82 degrees, depending on the CO2 ppms. The Silica foliar feed will help with this. Plants intake CO2 via the pores in their leaves and, much like humans, these pores only open up to sweat. If you're supplementing CO2 and your temps aren't between 78-82 degrees, you are wasting CO2 because the plants simply will not be able to uptake it as the stomatas will not open up below 78+ degrees Fahrenheit.

3) Be sure to stop the use of CO2 around week 5-6 of flower, as CO2 buildup also comes with ethylene buildup. Ethylene is a chemical that will halt the ripening process, which is the absolute last thing we want going into week 6+ of flower. A decent amount of semis running produce supplement with CO2 to produce enough ethylene to halt ripening of said produce, this way the produce is typically never ripe before it hits the shelves at your grocery store. This is great for farming/produce, not so much cannabis.

4) Make sure you have plenty of airflow and that your generator is closer to the ceiling of your grow, CO2 sinks, so you want the generator to be as high up as you can safely have it.

I think that covers everything.

HTH.

thanks for the input Kratos015.
I understand there's alot of negative stigma around the c02 bags but remember im not buying them, im using my own self made mycelium which means i can make adjustments to make it perform as needed, aside from that i've personally witnessed readings of 1200+ppm using an Exhale brand c02 bag in a similarly sized tent to mine so i know there's atleast some good ones out there but personally im not trying to push it to 1500 or even 1000, i just wanna sit around 500-600, slightly more than what the outdoors is so i can run the temps a little bit warmer and exhaust less frequently and of course ill dose the nutes a bit higher to accommodate that. As of right now my plan is to get a co2 meter and make a bag and see what readings i get so i can start dialing it in.