Milles may live and grow at 100 par, but I can say for sure that some of them ie the ORA blue mille will definately not color up to a nice shade of blue under those conditions, I have a mille that is a sick looking hot pink at decent par levels 200+ for example and if its placed low in the tank it will grow and live but it changes to a green mille, loosing its hot pink color. My point is that going by my own experience I have found that SPS may survive and even grow at 100 par but they will not show the best coloration that we strive for in an SPS tank.