i have tried many different things to increase growth in my corals including different supplements, various photo periods, over feeding and large water changes, etc, etc, etc... the one change that hands down brought on THE MOST growth in my sps was switching to a 10k bulb!
+1............
Had been sometime using 10K in my fragging tank then changed to 14k and discovered the slow growth.
So how do you explain this observed difference when compared to this study:
http://www.advancedaquarist.com/2008/12/aafeature1/