by warra48 » Sunday Dec 30, 2012 7:58 pm
The volume of CO2 means exactly that.
If you have 2 volumes of CO2, it means you have dissolved 2 litres of CO2 at atmospheric pressure into 1 litre of beer. At least, I think that's what it means!
BeerSmith has a carbonation tool which suggests a range of CO2 volume for a particular beer style, although I'm sure that information is available elsewhere.
Ultimately, you'll work out your preferred level for different styles if you keep notes of what you do with each of your batches.