I didn't know it was so harmful for bettas, i read somewhere that it should be done with each water change because it is soothing for them and helps them adjust after a water change. I've never added salt everyday, only with water changes which is once a week, but i will def. stop adding it.
I find the whole betta care confusing tho. There are TONS of articles out there but they all say something different. Even the experts don't agree on all points.
anyway, i guess all i can do is try to keep learning about what is best.
Thanks for your advice :)