Bryopsis and Magnesium

[Acro-Phobia]

My system is humming along great, but I have what appears to be Bryopsis growing in my overflows. It keeps trying to spread back into the tank and is also blocking water flow into the overflows. I was told to try killing it by raising magnesium to 1600. I'm looking for a second opinion before I do something radical to my system.

My concerns are, 1. what affect will high magnesium have on my corals (mostly SPS and a few LPS) , 2. will this cause a amonia cycle if it dies off quickly, 3. are there other problems assosiated with doing this.

Lastly, if this is an okay method to rid the system of Bryopsis, what is the best way to jack up the mag level to accomplish this.

125 gal tank, 40 gal frag tank, 55 gal sump, 20 gal fug: total approx 200 gal system.

Cal - 400
Alk - 10.2
Mag - 1200
Temp - 77.7 - 79
Sal - 1.025
N03, P04 - undetectable

Running Phosban, carbon, Kent Tech CB

Thanks

Alan