I am afraid that there is no ...

I am afraid that there is no easy and economical solution to remove the Calcium. You could consider :

• Ion exchange (Calcium will be replaced by Sodium)
• Lime softening, depending on bicarbonates concentration (settler+sand filtration). main drawback : sludge handling
• Catalytic Caustic Soda softening: upflow reactor+sand filtration (pellets handling has also to be managed)
• Nano filtration
• Reverse osmosis

Afterall Calcium is good for health...