This one seems to cause some very negative comments.

Alright, I've got this idea. Boy, that sounds like the beginning to an
end.

I figure I can drop dry ice in a tank, cap it with a regulator and have
CO2 for some period of time for my planted aquarium. Obviously it will
require more than a handful of dry ice and chances are it ain't quite
that simple. Right now I am building a tank with a mouth wide enough to
accept an entire piece. I figger I'll pack the stuff in there like the
old shotgun wadding with a length of 2x2 or something until it's full,
and cap it.

I run a search on this over the web and the Google groups. I got the
same response: "DON'T DO IT, IT'S TOO COMPLICATED"

What's up with dat? Any particular reason? I don't want to hear that
the stuff is not sanitary either. The air in my house probly ain't
sanitary after a nice homemade bowl of chille. Heck, it's free......
They pack ice cream in it at the gas station (they sell ice cream in
cones) and they just throw it away.