I see you have spectral data for the XM DE 20K on an IceCap electronic balast. I thought they weren't compatible ?
From the
bulb's description on marinedepot.com : The XM double-ended 20000K metal halide bulb offers excellent coloration and good intensity. It is white with a strong blue tint. It brings out the fluorescent pigments in corals nicely. Fluorescent supplementation is usually not necessary, but can be used for added intensity and to simulate dawn and dusk. This bulb will work with a standard magnetic ballast, magnetic pulse-start ballast or magnetic HQI ballast: it is not compatible with IceCap electronic ballasts.
So what's the story?