Ok so this is probably a stupid question, but what about the CO2 fire extinguishers? Just out of curiosity...
But I guess the fire extinguishers leave behind foam or some residue right?... Anyways just a thought!
CO2 fire extinguishers are normally pure CO2, so that would work - the only problem being the speed at which it comes out and the way it tends to be extremely cold too, neither of which will be good for a terrarium! If you fit a regulator to it (as some aquarium plant people do) you could fill the terrarium with CO2 quite easily.
I have just discovered that my two orchidariums are crawling with teeny tiny centipedes and was pleasantly surprised to find this sticky!! Where do I get dry ice from though??
Hope it's ok to re-open an old thread. I tried this method last night using dry ice. Becasue my tank is a plaudarium (with water containing fish at the base), I had to remove the plants & do the dry ice process in another container. I used an esky which obviously does not have transparent sides as does an aquarium. My query is, how does one know when the container is full of CO2? When I did the procedure I left the lid open only a small gap of 3mm I found when I opened it a couple of minutes after putting the cups of dry ice (with warm water poured over it) in to take the cup out (so as not to lower the temp too much & kill the plants, that the fog no longer filled the esky. I'm now not sure if this is becasue the CO2 had become transparent or becasue it had dissipated & been replaced by air.
I'm not sure you even need the dry ice. Burning a candle in the terrarium until it snuffs itself out will remove most of the oxygen. However, keeping plants in such an oxygen-starved environment indefinitely will kill them. Plants do need some oxygen readily available for respiration, they just don't die as quickly without it. And yes I'm fully aware that they do produce O2.
I did an experiment when younger of putting a candle in a sealed terrarium and letting it burn out. The plants were dead by the next week. I bet if I ventilated it within a day or 2 they would have flourished instead.