[hahnmeister]

Id just add 2-4 rows of T5s to those existing halides, maybe swap the reflectors for lumenarc 'stealth' reflectors for better penetration. The 150wattDEs can be swapped for a high output 10,000K like the XM/XDE. Then the T5s would be a combo of 2x blue+ bulbs and 2x super actinic bulbs.

The more daylight looking halides have an output that is similar to what many bluer 250watt bulbs have, but the T5s, with all their blue and actinic, will cover up all the yellow. Corals love this combo as well because there is loads of blue and actinic, but there is also loads of daylight... a full spectrum that no halide can provide unless you run 10,000Ks.

The result? A nice 'dayblue' look, almost icey except for a hint of yellow in the output.

For your 125g tank, I would suggest the Icecap 660 ballast, then 3 of the 60" Tek2 reflectors, and 3 sets of endcaps. Then just do two ATI blue+ bulbs and one Sfiligoi Actinic (60" bulbs). The IC660 can run three 5' bulbs on its own then, which is really all you need. The alternative is running a split bank of 3' T5 bulbs (6 or 8x 39 watt bulbs), but the output isnt any greater really, and it just means you have more bulbs to replace every year or so (and 3' T5s cost within a a couple dollars of the 5' ones.