As I am sure you know, this star is NOT reef safe. All of your corals, anemones, clams, snails, etc are at risk, regardless of how much you spot feed.
IMO, your specific gravity is rather low for these stars (1.025-1.026 is better for inverts). Your temperature, IMO is very low for a reef.
Many of these stars do change colors with growth but I am concerned about some of your parameters as well just in terms of long term care.