Problematic Mg and Ca.

[Alegeo_dragonette]

When you use the salifert kit for magnesium, it does not change color with a whole syringe of fluid added?

But with new salt water it does?

Exactly

 

[Randy Holmes-Farley]

Exactly

I'd add a second syringe of titrant, dropwise, and get to the color change, to get an actual value (you add the two together) and be sure it is functioning properly.

 

[Saltyreef]

Looks like youre not the only one having this issue. Heres a review from BRS. Same issue as yours.
No wonder its discontinued.
Id switch your salt mix and use a tried and true salt like red sea blue bucket if i were you.

Cheers!