From oceanfloor:

Hey thanks for the info, expecially the reminder to purge the hose. I last dove October 24-25th so the air isn’t too old. I’m usually in the habit of refilling my tanks after every dive but I thought that was my last dive for the season, but NOT. I’m hitting Circleville Quarry today.

Q. When they refill the tanks, do they just top them off or do they purge them and refill?