It's probably not the SPG or hose itself that's leaking. All high pressure SCUBA hoses use an air spool with two tiny #003 O-rings to mate the swivel connector on the female hose fitting to the male fitting on the hose or wireless pressure transmitter. If the air spool O-rings are worn, the assembly can also have a slow leak around the swivel. Even when an O-ring has failed completely or the spool is omitted entirely, a tiny flow restriction present in the high pressure port of the regulator and/or the male hose fitting will cause a leak to be much slower than expected. We recommend replacing the air spool, or at least the spool O-rings, whenever replacing the hose. See our video on Leaking SPG Spool Replacement.