What's the difference between CO2 exchange VS. Back-Up CO2 cylinders (spare cylinders)?

Bubbles 101: Our carbonating cylinders are the heart of your Sparkling Water Maker. It perfectly fits your Sparkling Water Maker and contains colorless, odorless, incombustible CO2, used to help create the bubbles.

With a CO2 exchange, you return any empty SodaStream cylinder and just pay the price of the CO2 for a new cylinder. You can easily exchange your carbonating cylinder via a SodaStream stockist near you.

A spare cylinder is there so you never run out of CO2. You pay for the license of the cylinder and the CO2. SodaStream recommends having at least 3 cylinders on hand, so you’ll always have bubbles and so you can exchange 2 at a time.