The Control Valve and Regeneration
The control valve is the traffic cop in your water softener system. It determines when it is time to clean those plastic beads which are now coated with calcium and magnesium. Older style units use a timer, newer models use a computer controlled meter that determines when it is time based on actual water usage.
To clean the beads the water softener uses a process often called regeneration which consists of three cycles: Backwash, Recharge and Rinse. Let's take a review of each cycle.
Regeneration starts with a backwash cycle where the valve reverses water flow in the tank and flushes the tank of debris. The debris is then eliminated out the drain.
Recharge or Regeneration:
In the Recharge cycle the salty brine solution is pumped into the mineral tank. The highly concentrated salt solution with its positive electrical charge is attracted to the negatively charged plastic beads and forces the magnesium and calcium off the beads.
The salt or potassium by itself is not positively charged enough to displace the magnesium or calcium in normal concentrations, but in the highly concentrated solution of brine, it is strong enough to force the calcium and magnesium off.
The excess magnesium and calcium rich salty water is then flushed out of the tank and down the drain.
The tank is then filled and rinsed with water and the process repeats itself. The beads are now coated with salt. As the calcium and magnesium from the hard water are attracted to the plastic beads, the salt, now in much diluted quantities and smaller electrical charge, is forced off the beads and is suspended in the softened water.
When the beads become nearly all coated with minerals, the control valve starts a new regeneration cycle and cleans them again, flushing the hard water minerals down the drain.