list your pony bottle size options / reasons

[wukuu]

When I am calculating my SAC I try to do either a 30' or 60' dive and take a measurement when I have no load, sitting around or so, a measurement when I am doing standard swimming, and a third when I am under heavy stress.  If I am then trying to figure out what kind of extra air to carry I tend to use my heavy consumption, because if I am using it, things probably hit the fan and there will be a bit of stress there.  Better to have a bit to much air then not enough.