I am curious on this one as well. I have a GSP rock that the polyps have been staying retracted more than extended. I had a new addition to my tank and the problem seems to have begun since then. I added Xenia and began dosing 1 drop of Lugol's solution (diluted in one cup of tank water prior to addig to tank as per the directions) once weekly. Amm, Trite at 0, Trates at 20 (can't get them down), phosphates at 0, KH 100, Calcium 480, Dose Tech Calcium Daily, Coral Vital Daily (1ml each), DT's every three days (1ml), SG 1.024