Unlike normal chlorine that is used up when you get in, SmartChlor continues to maintain the same level which is up to 75% less than hot tubs using Dichlor (standard hot tub chlorine). That’s why it is called self-regulating. It goes to work when the hot tub needs sanitizing so there are no frustrating yo-yo chlorine levels. This time-released method is also why less shock is needed to maintain the hot tub. When the SmartChlor Cartridge is depleted the system will flip over as a visual reminder to replace the empty cartridge with a new one.