We live in an area with naturally high magnesium in our water. This spring my pool (28 foot round above ground) was more than half full with rainwater/snowmelt. I did the same as every years filled it from our well. My Taylor test kit tells me my CH is about 500 ppm. We have fairly low naturally occurring calcium here. Outside of my years and years of using the powdered chlorine "shock" that I now now is not the best choice, is it possible the CH test might show the magnesium as calcium? I have been reading a lot on this lately and got the impression from somewhere that this could happen. Of course, I could be dead wrong too.
We drain the pool down to 18-24" each fall and end up with at least 3-4 feet of water in spring from snow, so I'm a little confused on where I'm gaining so much CH. My test kit says I need to drain and replace 49% of my water, but I don't know of a "soft water" source locally.