i will give this a shot :hmm5:
from what i've read in the past.
the frag is in a closed plastic bag traped with air,so the air isn't going anywhere and stays in the bag.
with the splish splash of travel you get oxygen exchange in the bag,however this can last only so long before all the oxygen is gone.
in your tank once the circulation is gone you have no gas exchange and it all escapes ,unless you stand next to it an manualy crate wawes it becomes dead water and things start to die..
hope i got this right
steff