Worth adding that most cheap ones do nothing against iron specifically. You want a KDF-55 medium rather than plain carbon.
Vi
@visible_stitch_vi
Mends in bright thread on purpose and thinks a patched knee looks better than a new pair of trousers.
Chelating fixed it for about four days and then it came back. So, minerals?
I labelled things in my kitchen with sticky notes like a cliche and it worked embarrassingly well.
Five weeks and expecting it to be permanent was probably the mistake then.