Never tried that technique of raising mag to those levels but then again never had to. Hopefully someone can chime in that has experience in this. Good luck
The bottles of kent marine have dosing instructions. Buy a couple bottles and a magnesium test kit. Follow the instructions on dosing and test every day until you hit 1500. Hold it there for a week or so until it starts to die off then lower the mag back down with regular water changes.
This is how I did it but everyone's tank is different and reacts differently to changes. I also only keep mushrooms and zoas. So I can't make any claims on how safe this is for other corals.
I always keep my Mag at 1600. Got the info from an ole time reefer. My LPS love it My Clam doesn't seem to mind either. As for my softies well they're just outta control period-lol.