Thank you for the replies. I haven't measured TA for about a year. At the time it was in the desired range but barely. I can't remember if it was at the high end or the low end. I assumed it would not change.

I changed the pool water shortly before I added the SWG so the CYA from the dichlor is very low. I remember measuring it. The pool gets little or no sunlight so that works.

It's probably the borax then. So that will work fine for a while, but when I finally will have to add acid, I suppose I will have to add a lot!

I am wondering if there is something leaking into the loop that is providing the negative ions while slowly dissolving some important part of the pool :-|