Mg: JBL showing 1280, SALIFERT showing 1800 ?! Which one to trust?

[Chepre01]

Hello,
I am super confused..

JBL Mg Test turning color after 17 drops. So 1700 - 420 (Ca value) = 1280 mg
Salifert Mg test needs more than 1,0 ml to turn color, like 1.2 ml which would be around 1800 ppm cause i dont need to substract here Ca value)

Testes both several times, gettine always this kind of range.
So, this is not even close, huge difference actually?!

Is there any way to test which one is the correct number?

 

[twelvefive]

Mix a fresh batch of salt water and test it, see which is closest to what the salt mix should be.

 

[Chepre01]

Mix a fresh batch of salt water and test it, see which is closest to what the salt mix should be.

sry for this stupid question... but if i have1 liter of saltwater with 35 salinity, how much MG should this be?

 

[twelvefive]

sry for this stupid question... but if i have1 liter of saltwater with 35 salinity, how much MG should this be?

Which salt?

 

[Chepre01]

tropic marin pro reef sea salt

 

[twelvefive]

Should be around 1350