I wish I had known it before buying one for my shrimp tank.
The regulator on my 75 has a brass to brass connection - no seals needed. It came from a welding tank setup. I used the 5# tank for awhile and fitted the connector piece from the CO2 welding regulator to a new Med-Tech high quality regulator from an oxygen set up. I only have to adjust it twice a year when we go from cold to warm and warm to cold seasons.