On April 5 at 11:20 the helium tank pressure was 720 psi with the regulator at 40 psi just before I put the sieve slit in.
On April 5 at 19:18 Alex reported that the pressure was 600 psi at 40 psi on the regulator when he took the sieve slit out. That roughly means we lost 120 psi over 7 hrs or 17 psi per hr. At that rate a tank should last about 43 hours. Not too good.