Tom, thanks for your post. I have a 20 oz. paintball tank fitted with a special valve that I attach to my Sodastream. Sodastream CO2 bottles are expensive, this is a much cheaper alternative to getting CO2 than from Sodastream. In the USA where I used to live, it was easy, cheap and convenient to get my paintball tank filled with CO2. Now I find in the UK that it's much more difficult. Is it possible to get my paintball tank filled with CO2 somewhere? A dive shop, or a gas supplier, or...?? Homebrew supply?