Proportional brining is a method of regeneration where the amount of water added to the brine tank is “proportional” to the remaining capacity of the softener when regeneration occurs. This means that the salt usage will vary depending on how much capacity is left in the unit. Theoretically, only the media that has been exhausted is regenerated. Every softener (except for duplex units) has to regenerate before it uses 100% of its capacity, otherwise the household would experience hard water. Proportional bringing is achieved by measuring the unit's full capacity versus the softening capacity used. The controller automatically adjusts the brine fill time (which regulates salt consumption) to the capacity used.