You can only use the pink CO2 cylinders. But you can swap them anywhere. Lidl and Aldi are the cheapest. It's even cheaper in Germany if you live near the border.

Officially, you can only use the pink cylinders. However, there are adapters available on Amazon, for example, so that you can continue to use the cheap cylinders from Aldi/Lidl. As this makes the bottle slightly longer, you have to remove the base at the bottom, which is very easy with this model.