Best Test Kit For Magnesium?

[IonicBond]

Another vote for Salifert

Or Triton

 

[ReefTeacher]

I really like the Tropic Marin Mg test kit. It has an unusual but very clear color change. There is a 2 step titration where you determine probably a larger hardness concentration, then subtract out the part that is not Mg. I find it very reliable.