I maintained a bromine tub for about 7 years. The granular bromine is used mostly at a refill to get the bromine level up to where you want it right away. It takes some time for bromine tabs in a floater to get the levels up. I used to add a little granular when I knew the tub would see major use, like right before a party. If you have ozone and/or use a Frog mineral stick, you can keep your bromine levels very low, and it is a real easy way to maintain your tub- bromine floater and no need to add anything on each use. I found it about the only with three kids who used the spa with friends. They will not remember to follow a system that requires adding clorine or mps before or after each use.