RE: CO2 Problems

        Sorry to disagree with every one but the ratio of yeast will
not cause his/her problem.  I have been using a full packet of yeast
with no problem and 2 cups of sugar into a 1/2 full Gallon bottle.
        I will agree that temperature COULD be a problem if it is much
under 70 degrees F.  However from experience I  would look for a leak in 
the air line or a clogged air stone.  If the bottle is expanding then 
then it is a clog.  Otherwise look for leaks.