Well sometimes I stop by the local microbrew and bring a gallon of it home. They pour it into a milk jug and put one of those push on type caps on it. It stays good all evening long. Now, what if I wanted to save some for the next day? I've done that before and the beer went flat. Now knowing what I know from reading here and bottling my own beer, what could I do to get it from going flat? Add some corn sugar and get a tighter seal?