Softening pool water

I live i Sothern, CA where all we do is add water to the pool.
Tap water is 300ppm CH, so the level just builds up and up.
I'm about 1100 now and looking for any solutions.

I know I could drain and refil.
I talked to a guy who does mobile RO treatment.
I've seen mention of magic "polymers", but never what they actually are.

I've also seen some intriguing stuff on Lime Softening.
Problem is, I have a cartridge filter and no way to "vacuum to waste" without some replumbing.
If there any floculant/clarifier that would get the precipitate out?

Has anyone actually tried this with success?
I don't want to end up with a permanently cloudy pool.

My first questions would be: Why is your CH going up? Are you using cal-hypo for chlorine? Is your pool hard-sided (as opposed to vinyl or fiberglass) and is it curing? Are you getting MASSIVE evaporation so the water gets more concentrated?

What's the CAUSE of rising CH because a level of 300ppm is perfectly fine in ANY pool.

Continuous evaporation.
I've never pumped water out of the pool (never enough rain to do it).

In the Summer, I add a couple inches a week of 300ppm water.

By the time I've added 15,000 gallons to the pool, I've got double in it.

I guess after 4 years, I've added 45,000 gallons.

===
SWCG
15,000
Pebbletech.

I have the same problem, high CH fill water and high evaporation. I choose to refill because it is the cheapest easiest option.

Do you cover the pool when you are not using it? That would tend to inhibit evaporation. If I find that gets the water too warm, I run my solar panels at night and they act like radiators instead, cooling the pool.