Put the salt in the brine tank. Yes, just like a giant, heavy bag of salt pellets. Pour them in. You cannot put too much, but do not fill it to the absolute brim. Leave some room for the water.
Turn the water back on, but do it slowly. A fast rush of water can damage the valve. Open the bypass valve halfway, wait for the hissing to stop, then open it fully.
Check every connection for drips. Run your hand under each joint. A pinhole leak will tickle your finger. Tighten things gently—brass fittings crack if you are too aggressive.
Set the Timer
Now, program the control head. This is the brain of the operation. Set it to regenerate at 2 AM. Everyone is asleep, and the water pressure is highest.
If you have an iron problem, set it to regenerate more often. Most units have a dial or digital display. Read the manual. Yes, read the manual. It takes ten minutes and saves you from calling a plumber.
Finally, run the softener through a manual regeneration cycle. It makes a few gurgling noises, then quiets down. That sound is the sound of victory.