I was thinking about the 10K XMs. I'm just worried about too much heat and light over the 75 with those rather than the 20K XMs I was planning on getting. The lights sit about 8 to 10 inches above the water level now so that may help with heat issues.

Even as old as those bulbs are they still really got my corals to color up more nicely than the sakis with actinic supplement. But they do need to be changed out, hence the decision I'm attempting to make now.