Originally Posted by NoranaC
When you say add 1/4 tsp of sugar, do you mean one 1/4 tsp for the gallon bottle, or one 1/4 tsp for each 2 liter bottle?
Well some amount of sugar will have been consumed to make the co2 in your current bottles. Some of the co2 will cary through to the new bottles, and some of it will be lost. How much I don't know. Not knowing exactly how much sugar you started with, I am guessing (litterally here) that a 1/4 teaspoon in a 2L will help it not be flat later. - also I'd feel safe doing 1/4 teaspoon on even a smaller bottle like 1L or even .5L/ 16oz. hence why I buckshotted .5L
IIRC, the soda syrup I had wanted 1 gallon, 2.25 cups. Or 2 cups equivently sweetener(lower cal/diet) and 1/4 cup sugar for priming This makes 4 tablespoons of sugar for carbonation, or 12 teaspons. The problem here is that I and you don't know how much carbonation there is in soda bottles when you finish transfering.
I free admit this is a WAG (wild beast guess). Now that said, some math could be applied and better numbers found. I do know that plastic soda bottles can take preasure. I think they can safely go 10 volumes co2 (that is 10x the volume of the bottle disolved in the drink. This is non linear with preasure, and I don't recall how.)
One last note, I'd put the sugar in and pour on to it. I think if you drop sugar on it, you are more likely to preform a mentos and diet coke moment, ok, not that bad, but it seems like the foaming would be worse that way, although honestly I'm not sure.