Help with Levels

[Sacohen]

Below are my levels from last week 3/9/13 and this week 3/17/13.

Date 3/9/2013 3/17/2013
Salinity 1.026 1.026
Amonia 0 ppm 0 ppm
Ph 7.8 7.8
Nitrites 0 ppm 0 ppm
Nitrates 0 ppm 0 ppm
Phosphates 0.03 ppm 0.08 ppm
Calcium 450 ppm 500 ppm
Alkalinity 9.0 dKH 9.8 dKH
Magnesium 1360 ppm 1440 ppm

I have not added anything to my tank in terms of trace elements, Liquid Calcium.
The only thing I did was a 10% water change on 3/10 with natural sea water from my LFS.

Would that be enough to raise my Calcium, Alk and Mag?
I know the Mag was at the high end of the suggested limited at 1360 so 1400 is not to good.

Any help is appreciated.