I carbonate chilled water first (this time of year out in my un heated garage) it only takes me overnight at 50 lbs then next day I add the syrup to the water. I was told that cold water alone takes the carbonation more easily then the complete soda mix does. I simply put water in my sanitized keg and shake it up for about 2-3 minutes at 50 psi you can watch the low presure gauge on my regulator and watch the CO2 flow. let the water sit over night under pressure and next day mix the syrup to the water. Slowly mix in the syrup in stages as it will erupt if you dump it all in too quickly. I add a little and close up keg and pressurize. let it settle bleed off pressure and add more syrup, repeat until it is all in. Let the soda sit for another day under pressure and serve.