Stuart is right. I give my customers a small container of granular bromine with start up. They add an ounce to get the tub started and don't have to set the bromine cartrdge but once (after it heats place it). Also, with heavier than normal usage, my customers add a small amount of bromine and have had no problems with the system. It has been very convenient. If you forget to place a new bromine cartridge in, the granular then helps in cleanup and maintain bromine levels until you do so.
