CO2 can be a pretty corrosive component in many tank environments. It may also be soluable in the fluid contained within the tank. It may not be compatible with the end use of the tank contents.
I have not failed. I've just found 10,000 ways that won't work."-Edison “If Edison had a needle to find in a haystack, he would proceed at once to examine straw after straw until he found the object of his search. I was a sorry witness of such doings, knowing that a little theory and calculation would have saved 90% of his work.- Tesla
CO2 is not an inert gas. As Big mentions it is acidic with any moisture at all. CO2 was a common blanket gas years ago but mostly replaced with N2 or natural gas. CO2 could also react directly with the product in the tank. What is the source of CO2? Most likely it is not even economical to use.
