We also use Soda Stream and have the adapter kit and purchase CO2 in St Martin. I use the charged water when mixing with my homemade Ginger Ale as well as the syrups we get from Soda Stream. We Love It and it is our #1 itme we love for our boat. Last year we went together with a couple other cruisers and had a shipment sent to Grenada via Tropical Shipping. The reference to the individual CO2 cartiges for a singel serving sound very expensive.