I've been using the inline spa frog bromine for almost 5 years without any problems. Yes, a bromine "bank" needs to be established each time you change water. I usually grind up a bromine tab, mix it with water and dump in in while the tub is filling. Generally, I can keep the bromine cartridge set in the 1-3 range. Many times it stays on the lowest (1) setting its whole lifetime. I usually get a month or more before the bromine is spent. No fuss.