Lately I've been filling my corny kegs from the fermenter (primary and secondary) through the liquid post, the fermenter airlock is replaced with a hose to the gas post to equalize the pressure. I have read several posts where some brewers fill the receiving keg with StarSan and force it out using CO2 tank pressure. This could leave quite a bit of sanitizer in the bottom of the keg, I think. The intent is to limit the beer's exposure to oxygen. I was wondering why not just purge the receiving tank with CO2, which is heavier than oxygen thus the O2 rises to the top of the keg and is first forced out as the keg fills. I would think that this limits the O2 exposure, eliminates the StarSan fill and purge step, and leaves no residual sanitizer in the beer. I was curious if anyone has been doing this and are they satisfied with the results. I can say that my dry hopped beers have a stronger aroma when done this way as opposed to filling through the keg or fermenter opening.