Holy freakin undata!!!! David you did an amazing job with this tank . I admire your coral selection. All these new aussie corals have me wanting to add a million things. I have to follow your approach a little more. I have the same fixture and I've been playing around with different halide bulbs. With the geismann electronic ballast, bulbs are burning different colors that I had in the past with my PFO HQI's . My favorite 250w DE bulb used to be a 20k helios, which became 20k EVC. This bulb is too blue in the Giesmann.
IMO the 10k XM is a little too white but I haven't tried it on this ballast so maybe it will look better. Believe it or not the best color I have seen on this ballast is a 14k Sunpaq bulb. I know it's a poor brand but the color is very good. The bulb itself is not as white as a 10k and not as blue as a 14k. I run it with 3 blue+ and 1 fiji purple. I get a good balance of color. Your undata would look insane under this combo.
Good to see you posting David
and LMK if you upgrade. I may want to transfer my 60 into your 90