How Do I test Above Mg Limit?

[ReefNut]

I'm getting ready to start a battle with bryopsis.
I want to raise my Mg to 1600 but my test kit(salifert) only goes to 1500.
How can i accurately measure above 1500mg/l?
Thanks

 

[Sumbub]

Fill the measuring needle to the full 1 mil and start dosing the second time around. When you put in the full 1 mil, it's 1500. GL with the battle. Keep it up there for 2 weeks.

 

[ryangrieder]

Salifert mg test kit has a formula on the instructions. I raised my mag up to 2000 and was able to test it with the salifert kit.

 

[ReefNut]

I can't find a formula for going past 1500ppm.But looking at the graph,for every .02ml of reagent mg-3 the magnesium concentration increases by 30 ppm.
I have assume this will be accurate enough?