Fiji Acropora.  Acroporas are one of the corals that are the most difficult to keep.  If they are not happy with your parameters, they will change colour to let you know.  Most of the time it will be your Alkalinity that is too high or too low.  Water changes in a SPS tank is needed, because of the need of other elements in the water.  Having a dosing pump which you can control your Cal, Alk, Mg and having good test kits plus testing weekly or more is needed.  Amino Acids are also a great addition to keep it's nice colours.  We use Tropic Marin for all of our dosing.
 
Requirements
Lighting: Low  about 250+ par
Flow:  High
Cal 400-440, Alkalinity between 7.5-8 Dkh, Mg 1400