Oh, wish I copied the original site of this post. It was so good I hardcopied it. It might have been from this forum, or another, I suspect here, though.
Anyhow, "Tim" found that he had a leak at the bubble counter, the needle valve, the check valve (replaced that with a metal CO3 check valve with barbs and a tightening hex nut), found he had to replace washers between the cylinder and regulator at each tank fill up, and then found that 30 % of his loss was the silicone tubing. Replaced that with CO2 proof tubing from marine-monsters.com. He mentioned the test kit, from welding shop or beverage supply house, said that soap works for large leaks, but appa ently he needed this stuff for small leaks. He said that 80% of his CO2 was escaping unused. And weigh the bottle to see the usage.
Just a "head's up", trying to help pass on what seemed to be good info.