The last thing to mention about carbonation is that a soda stream can barely carb water properly because it carbs it too fast, at too low of a pressure, and there's no agitation, so it only absorbs a small amount of gas and the rest is forced to erupt out when the pressure is relieved, which is why anything with sugar in it will foam up and create a mess. That's also why anything carbed with a soda stream is intensely carbed for only a few minutes then it goes really flat, really fast. I carb in 2 liter bottles between 20-45 psi depending on what I'm carbing, and agitate it which makes it absorb a lot more gas and stay carbonated for MUCH longer. The soda stream only carbs to 15 psi and you can't shake it, which is why it didn't work on that beer you tried. If you chilled that beer in a 1 or 2 liter bottle topped with a carbonator cap then carbed it to 20-25 psi, shaking it and refilling the gas a few times, it would have been perfect. It's what I do because I'm too impatient to bottle carb.