There are a few ways to get more bubbles in your SodaStream. One is to use less water. The less water you use, the more concentrated the carbonation will be. Another way to get more bubbles is to use colder water. Carbon dioxide dissolves better in cold water than in warm water, so using colder water will result in more carbonation. Finally, you can increase the amount of time that the soda is left to carbonate. The longer it sits, the more carbonated it will become.