What if you were to install a water softener into the pool plumbing, then when the CH gets too high, you run a couple batches of water through the softener to remove the CH. I could then see that if you also ran your auto filler through the softener you should be able to stay on top of the CH issues.
Has anyone done this? I know that you can't use a home softener to reduce the whole pool at once due to capacity issues, but you could do it incrementally. then keep on top of it.
For <$800 it seems like it may not be a bad thing. Of course it would be nice if you could just measure the hardness and turn on the softener when needed. With the flow meeter the softener it would know when to recharge and all.
What I don't know, is the effect of the chlorine, borates, etc on the resins in the softener.