I posted a few pics of my SPS in this thread
http://96.31.76.198/vbulletin/showth...005#post773005
While I lost a little "pop" in my colors, on a very few pieces, overall I'd say LEDs can successfully grow SPS. My growth has not slowed, polyps are the same, colors are mostly the same. This is with 6 x AI Sol blues. Either your light doesn't have enough power/intensity, or the water quality issues you mentioned are affecting the corals.
GOOD LEDs are perfectly good for growing SPS
