Originally Posted by acidrain
A leak on the high-pressure side of the reg is almost impossible to find with soapy water (it blows away the soapy water with no sign of bubbles).
To find those, you'll need to submerge the tank up to just the edge of the gauge.
Keep looking, it's there somewhere.
I assume submerging the regulator itself is bad for it's longevity
So, connect the tank to the regulator, pressurize, and put the tank into the water as well as the line (all the way up to the regulator connector) and hope that I see something?