Using bottled CO2 is many times more environmentally responsible than producing more CO2 by combustion, and doesn't add heat or humidity to your room (both of which are unwanted byproducts of combustion).
Bottled CO2 diverts CO2 from industrial processess rather than allowing it escape into the environment and contribute to the global CO2 budget. Instead, it is sequestered and used in greenhouses where plants can convert it to fixed carbon (where do you think the carbon in THC comes from?) and available O2.
There is little doubt, although filling CO2 tanks is a hassle, it is better for the environment, and better for your room... adds no heat, adds no moisture.
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Obviously you did not bother reading the link I provided (and are totally misinformed about the other part)
The CO2 generator I linked to introduces a very neglectable amount of heat to the room it is installed in.
Even IF it was to add heat (such as more conventional models do) they do not add moisture, they only condensate already existing moisture.
From all the grows I have visited over the years most with more than "just" a closet size grow use dehumidifiers anyway, those are mandatory for speeding up a plants metabolism by enhancing the evaporation rate due to lowering the humidity in the plants environment. Not to mention controlling (avoiding) mold due to the (lower) humidity.
Bottled CO2 diverting CO2 from industrial processes being an advantage as you wrote is an absolutely pathetic claim in the context of using it for our purpose!
By generating CO2 with a combustible gas whether that is Propane (which is Liquified Petroleum) or natural gas you are not generating something which wasn't there before already, just in a different form! You are just converting one form (Propane) to another (CO2).
So how is using bottled CO2 as a result from an industrial by-product better for the environment than using Propane???
On another note bottled CO2 is NOT an industrial by-product!
I am not going to bore everyone about the technical details on how it's done...just Google it yourself if you're interested.
So...using bottled CO2 is more of a hassle than everything else.
Bottled CO2 is not any better for the environment, the bottles have to be trucked around before you pick 'em up & you will also burn gas to keep getting them.
Not to mention lugging around heavy @$$ bottles is a safety issue for most people growing, propane containers also used for BBQ's etc. available @ every Walmart are no problem to be brought to any house hold.