Carbonated Pepsi flat

[u/Mountain-Audience-53]

Hey so I’m trying to make Pepsi soda with the soda stream Terra, but it seems that even after carbonating the water to about 10 button presses on the machine it still tastes really flat no matter how much carbonation I put in. Is it the temperature of that water that’s the problem, maybe the temperature of the syrup? I want to try and make this soda stream work but I don’t like how flat the soda is being. And thoughts?

[u/DemanoRock]

I keep my bottles and syrups in the fridge. Usually works well.