In many of those B-grade horror movies there were graveyards swirling with a cascading mist round the tombstones, (kind of like my living room on any Friday/Saturday night, hey, that's me in the cape with the fangs). That gas was sometimes carbon dioxide. It is heavy and so it sits and builds up like a thick fog that's fallen, like condensation vapor sitting on top of cold, frozen ground. It can be made by putting chunks of frozen CO2, also known as dry ice, into H2O which causes it to melt and turn back into a gas.
Can anyone see a problem with possibly using it as a source of CO2 in a grow room/chamber? Its advantages are that as well as aiding the growth of a plant it might also act as a coolant and possibly aid in keeping down the temperatures in grow-rooms/chambers. I think you can buy dry ice at ice cream factories where they used to pack it around boxes of ice creams when they were driving them in unrefrigerated trucks to fair grounds and swimming pool kiosks in Summer, (at least they used to when I was a kid).
*WARNING*
Just a note of warning for those of you who don't know, dry ice 'burns' skin, so I'd suggest thick gloves and tongs when handling it, unless, of course, you want to join me in my living room as the creature with the incredibly unusual skin formation patterns, and I do need a sidekick as I've found that it's really hard to hammer in those last couple of nails yourself on your own coffin as the Sun creeps up toward the horizon.

Damn that sucks. I played with it as a kid and my grandmother warned me.

Lol Did it work for you? Im considering it...

I have done it in closet grows. Your correct about the cooling factor.

It is a rather stable source in regards to continual emission of co2. however in order to achive enough cooling or enough measurable gas in a room you need to use a bunch of bins and a lot of dry ice. A block typical only last a day.

look into composting in your grow room, brewing beer in there, chemical pucks you drop into water, they will all give you a story to tell.

fermentation is a pretty easy one but you have to maintain it . baking soda and vinegar is a fun one ... if you do dry ice.. use a bucket wrapped in insulation with smaill wholes in the lid...
good luck i had some fun with all these ol tricks....

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blessed is he who shines light on they who walk in the darkness.

Mmmm, I tried the dry ice, it may well have saved my plants from extinction during a particularly stressful day, but at $18.50 a kilo block that lasts 6 hours, it's a treat they're only going to get every now and then!
Currently they're getting bottles of yeast with sugar and water thrown in front of their fan and, although it doesn't seem to be a very dramatic reaction, it's releasing a few bubbles here and there so it's economically more sustainable for me. I appreciate the suggestions, chronicprince and will give the vinegar and baking soda a crack as well.
As far as composting in my grow room goes, well I could just throw in a couple of my old socks, but that could possibly kill 'em all!

how do you get dried ice on a regular basis

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It was a pleasure to burn.

Ray Bradbury, Fahrenheit 451 (1953)

The dark man fled across the desert, and the gunslinger followed.


Gunslinger, Stephen King.

ice factories stock it

will they deliver it regularly? do i have to pick it up? just wondering the price and info and questiosn asked when ordering it...

__________________
It was a pleasure to burn.

Ray Bradbury, Fahrenheit 451 (1953)

The dark man fled across the desert, and the gunslinger followed.


Gunslinger, Stephen King.

like millenniumbud said, ice works stock it, but it's too expensive for me to use regularly at 18.50 a kilo. if you were to put it in a cooler with holes drilled in it and maybe some frozen ice packs with it too, it might last for 6 days per block ( the guy at the ice works said 6 days was as long as it lasted), you could also put it in a plastic bag with a release valve and as it evaporates, slowly release some of the gas to them every now and then, but there might be pressure problems if the bag's too small.
I have tried the yeast and sugar in a bottle idea but the reaction certainly wasn't dramatic to watch. Vinegar and bicarbonate of soda would be good I think, but I've yet to give that one a go.

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This is merely a creative outlet, and I do not use or condone the use of any illegal substance.

Dry ice is a rather expensive option as previously mentioned. Yeast/sugar gives off relatively small amounts of CO2 compared to what plants would consume. Vinegar/bicarbonate of soda is also a relatively expensive way to go as far as the amount of CO2 generated and the chemicals need to be constantly refreshed.

If one wants to go with CO2 enhancement then investing in a 20 pound tank with a regulator is likely the best option for most people and will be a cheaper option long term. Also, CO2 with a tank can be regulated to give off the amount of CO2 needed which is important for efficiency.

With dry ice who knows how much is being given off unless you measure the mass over time and do the calculations. It would also be difficult, for example, to set up a block of dry ice to raise the level of CO2 in your grow closet to a roughly optimal 1500 ppm and keep the levels there like a tank/regulator of CO2 can. A 20 pound tank costs about $15 to refill.

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Talk, without the empiricism to back up your statements, is dogmatic BS.