Ray Calvert wrote "This topic comes up fairly frequently. I would like to throw out two issues I have with using gas to top up. 1) One of the questions is how much gas is needed. Someone recently said that we need to remove all the air. Well that is not possible."
Ray - I believe you can remove essentially all the air from a carboy and especially from a Corny keg if you happen to use them. This technique is probably more suited to the kegs. Fill the keg brim full with water. Seal. Pressurize with CO2 (or the gas of your choice) while allowing the water to escape through the tap. When all of the water is gone the keg is totally filled with gas. For a carboy siphon slowly while filling the top space with gas. I guess you could use the gas to force the water out of a carboy using a two-hole stopper but I agree with those who caution against pressurizing glbutt containers.
That said I would never trust wine to a partially filled carboy or Corny keg. Learned the hard way years ago. However, several winemakers in our club do this and still make pretty good wines.
Can't comment on the air lock issue. I only leave about 1-2 inch space beneath the stopper in carboys and I don't see much movement in the air lock liquid...I use Vodka.
Bill Frazier Olathe, Kansas USA
