How often should Birm and Calcium Carbonate Tanks be Backwashed

[Lou N]

Hi,
We have a three tank water softener system with 10" x 44" tanks, for our well supplied water. Water flows through the system in the following order:

1. Calcium Carbonate
2. Birm
3. Resin

We are a three adult household, the water here is fairly hard and contains a lot of iron. How often should the the Calcium Carbonate and Birm tanks be back-washed? The system is setup with Fleck 5600 control heads with a 12 day skipper wheel.

What would be the best way to determine the regen cycle for the resin tank? I assume checking the hardness level would be a good start.

Thanks,
Lou