I'm not familiar with Elos test kits...but I do know that I've never seen an API test come close to accurate for alk
or calcium. So, that makes me not want to trust those results outside of the mag test.
Here is a link of the mix ratio for Red Sea's salt:
Coral Pro Salt is ideal for sustainable, accelerated coral growth.
So, with calcium supposed to be at 450 for their salt and you reporting that the dosing isn't raising the levels at all I'd want to use a more accurate test kit. I only ever suggest Red Sea or Hanna Checkers.