How long the media lasts can depend on the cfm rating of your skimmer's air intake, the moisture level where the reactor pulls in from, and how much CO2 there is to start with.
Lots of folks have had their first 'batch' of media run through quickly, but the next ones slow down.
Were it me, I'd look to venting to the outside first, and if that weren't feasible, do the CO2 scrubber.
In my old tank, all it took was a snorkel on my skimmer's intake, running that out of the stand and above the tank.