Well shit he coulda just said so, yo!

Okay enough fucking with the nOOb... CO2 is a gas at room temperature. You can't water with liquid CO2 because in fact it does not exist as a liquid; it is one of those peculiar substances that SUBLIMES, or goes directly from its solid form, dry ice, to its gaseous state as the temperature increases.
you want to add carbon in liquid form, you're stuck with adding sugars.
'kay?