Magnesium testing
 

I dont know whats goin on but when i test my magnesium i always get a lower reading compaired to the chris from age of aquariums in naniamo. For instance i got 1080ppm this morning and if i took it to chris he seems to get high 1200's. I dont get whats what im doing wrong...

Are you using the same brand of test kit? Salifert, ELOS, etc?

Have either past their expiration date?

The better kits include a reference sample. If you have that, you should validate the kit by using the reference in place of a sample from your tank. If you don't get whatever the reference value is, something is wrong and you should examine how you're doing the test and/or replace the kit.