I've seen the links on testing your thermometer, and how to tell if your hydrometer is even close (at least half of the time!). I Have several CO2 tanks, and just got another from a neighbour. Normally, I have always bought a new regulator, but this one has one already, and it is probably about 5-6 years old. I've always just assumed the new ones were okay, but I'm wondering if, on the new one (which is the used one), the dispensing pressure gauge is okay as well. Any thoughts?