I've read differning opinions on water in different recipes. The article hosted here on plantedtank just gives the sugar to yeast ratio, then says fill the bottle up with water most of the way.
But on this super helpful article, it recommends just using 2 cups of water for a 2 liter bottle.
So what I should be doing? I know having the bottle filled will allow the system to pressurize more quickly, but I don't know how water impacts the reaction.