Dosing Mg

[brittanyk]

Hi guys,
so since upgrading my 50 to a 90 I found out the hard way (levels got way too low ) that I need to start dosing.

I have had some amazing help and my tank parameters are almost perfect, but I have really low Mg.

Against my "tutors" advice I bought different type of mg supplement that he isn't familiar with.

I'm using brightwell MG. It says I can do a max of 10ml / 20gal per second day for dosing until levels are correct.

Problem is, I dosed it last night.... and tested this AM.... it didn't change at all.
I dosed another time... tested a few hours later and it hasn't changed.

What do I do? Is anyone familiar with this? TIA