Secondly, you don't need to weigh the cylinder to find out when the CO2 is
low. The high-pressure gauge will start to drop when there is no more liquid
CO2.

I agree, especially with a BIG co2 tank. The larger the cylinder, the
more CO2 gas will remain in the tank when the pressure starts to drop.
With my 5lb tank, it lasted a day or so. With my 10lb, it was still
stable almost a week after the pressure started dropping.


Chuck Gadd
http://www.csd.net/~cgadd/aqua