Hello,
May I ask which Walt Smith SPS species did you select? Some species can and do thrive in captive reef systems and others will turn brown and eventually STN and die.
From my experience, Fiji s.hystrix, a.sameonsis, stylo, porites are the easier ones to keep colour and have growth. The tabling types (e.g. a.hyacinthus), microclados, tricolour validas, thick branch types (e.g. a.gemmifera, a.monticulosa) are very challenging to maintain colour and have decent growth unless your system water is very clean and flow is very strong and random. Naturally, stability, lighting etc is also a must.