How much water to put in a water softener brine tank?

Modern water softeners automatically put water into the brine tank at the end of each regeneration. This water sits in the brine tank and dissolves some of the salt to create a very salty liquid called brine. This brine is sucked back into the water softener main tank during the next regeneration. The brine is used to "recharge" (sometimes called "regenerate") the water softener main tank. After the recharge, the softener can soften a set amount of water before it needs to be recharged again. Depending upon the size of the water softener, it can take between 2 and 8 gallons of brine per recharge. On most water softeners you can set the salt "dosage". Dosage is usually set in "lbs of salt". Each gallon of water will dissolve around 3 lbs of salt so if you set a dosage of 9 lbs, the softener will automatically add around 3 gallons of water to the brine tank after each regeneration.