So if you have a 23 liter batch (make that 23 kg for easy math) and the alcohol content is 5% that would mean that the alcohol would weigh 23*0,05=1,15kg and the co2 weight would be 1,265kg. Would the weight then be reduced by 1.265 kg or the difference between 1,15 and 1,265 (165 grams) ?