I had a TERRIBLE time with the Red Sea MG tests. I exchanged way too many emails with them, they refused to even consider that either there is something wrong with some of their reagents, or that the 'precision' that they insist their test be run with is unrealistic. I gave up on them - they wouldn't even consider replacing the reagents to verify what I suggested. Elos tests for MG are easier to use and I am finding more accurate. I do like the Red Sea Phos, Alk, CA, Nitrate - but not the MG-
send them an email to customer support and see what they say.
also, I find that sometimes 'we' focus too much on testing and not enough on observing health and behavior of our 'animal charges'
debby