Best lighting I have seen/know of for a 180 would be 3x250wattDE halides in lumenarc DE pendants, with two-three rows of T5s for supplimented blue+ bulbs and super actinic bulbs. The halide bulbs used in this combo are Ushio 14,000Ks. Its just an awesome look as well... corals really seem to love it.
As for your situation, with dual 400s, I would look for a 14,000K ish bulb... bringing up the daylight spectrums could go a long way. OR, you could add a couple supplimental T5s, bur not for actinic/blue, but for daylight/6500K bulbs to suppliment the red/yellow end of things.