Gas tank equilibration


I am a beginner with GROMACS and I have a question concerning a gas tank equilibration containing CO2 and N2. I am confused about which tau-p and tau-t to chose, which is suppose is different than a water thank. Does anyone have any tips regarding the choice of these parameters ?

For tcoupl I am considering using v-rescale and for pcoupl Parrinello-Rahman.
Regarding CO2 and N2 compressibility, If I understood correctly, it needs to be obtained from literature.

Many thanks for your help.