I have a copper ion system that requires higher calcium than normal — about 350ppm.

I had to change the liner, which meant all new water. I managed to overshoot the calcium adjustment, and ended up with 500ppm. Oops. Not a huge deal (the pH in this chemistry is about 6.8 so that prevents scale…never had a problem in 10 years with the system), but with water that “hard” it’s actually unpleasant to swim in.

So, I can fix that via dilution, but by my math it’ll take half the pool’s volume to get the Ca down to that level. (The water supplier’s water is about 100ppm.) With a 150K L pool, that’s an undertaking.

Is there an easier chemical way lower the Ca?

Thanks!
Michael.