CO2 bottle pressure gauge

> From: Jim Hurley <hurleyj at arachnaut_org>
> Date: Thu, 23 Jan 1997 19:16:32 -0800
> Right, more or less. In the last 5 years or so, I've bought 7 or 8
> 20 pound CO2 tanks. Each showed the exact same pressure (about 1200
> psi) and then, over a few days or a week, dropped to 0. As soon
> as that needle moves, the tank is empty - you're running on fumes.

(You bought 7 or 8 20# tanks in 5 years???)

Well, that's the opposite of our experience.  Our 20# tank lasts about
15 months on our 100g aquarium.  It generally sits at about 950 psi
(70 F room temp and 5000' altitude).  When it starts to move down in
pressure, i.e., the liquid CO2 is gone, it takes at least 2 months for
it to get to 200 psi at which point we refill it.  The regulator seems
to get a little flakey at that point.

Our 5# and 10# tanks do the same thing, except that it takes
proportionally less time for the "fumes" to be used up.  I think our
5# tank takes about 2-3 weeks to go from 950 to 200 psi.