Magnesium supplement - Is this accurate?

[ClubReef]

My current Mg level is 1200ppm and I'd like to ramp it up to approx 1350. I have approx 100g worth of water and I ran the chemistry calculator (Randy's calc) supplementing with Sea Chem Mag Advantage..it says I need ~143 tsb..is this correct? seems an a lot!

 

[Theace50]

I use a reef calculator also and when i had to supplement my MAG it would calculate ALOT of supplementing, this is normal. BUT dose 1/2 then test the next day and re calculate. then do the same that day. 1/2 at a time

 

[Satori]

And remember, Randy Holmes-Farley says to only increase your magnesium by 100 per day.