LostAtSea I will see if I can shed a little light for ya. Once you have achieved enough light for the tank, it all becomes a matter of preference on what you want the tank to look like. I will give you a little bit of info on some of the bulbs out thier and what they do with corals.
The Radium/Osram 20,000 K
and Sunburst 12,000 K
are both classified as Super Blue bulbs. Super Blue bulbs emit the vast majority of their light within wavelengths from 440 to 460 nm (high energy blue). They also emit small amounts of violet and green light. The narrow emission of this bulb happens to be located within an area of the spectrum where chlorophyll_a, chlorophyll_c2 and the peridinin pigments can absorb and utilize the light. The vast majority of the emitted light energy from the Super Blue bulbs is photosynthetically useable by the algae. These bulbs can actually benefit from a boost within the violet area of the spectrum. The 400 watt version of the Osram/Radium and the 250 watt version of the Sunburst lamps are both useable for shallow water stony corals.
The Ushio 10,000 K
and Aqualine Buschke 10,000 K
are Full Spectrum Violet bulbs. The spectral output of these bulbs is characterized by a large emission of violet light along with a secondary emissions of green, yellow and orange light. As Sanjay Joshi noted these bulbs trick the human eye into thinking there are emitting significant amounts of blue light. The significant violet light emission will provide plenty of light for the chlorophyll_a pigments within the algae. These bulbs will really benefit from supplemental blue light. Full Spectrum Violet bulbs will moderately stimulate the fluorescence of the green, yellow and red fluorescing pocilloporins. They will strongly stimulate the fluorescence of the blue and linked red fluorescing pigments. These bulbs only provide a weak amount of light that can be absorbed by the pink pocilloporin pigment. The 400 watt version of the Ushio and Aqualine Buschke are acceptable bulbs, while the 250 watt version of the Double Ended HQI and Aqualine Buschke are also acceptable. Actinic bulbs or Super Violet bulbs are best used as supplemental lights for bulbs that are deficient in violet light emission.
The Iwasaki 6,500 K
is the only bulb classified as a Full Spectrum Green bulb. This bulb emits the highest percentage of its light within the green and yellow parts of the spectrum. It also emits significant amounts of violet, blue, orange and red light. About 60 % of the total light emitted by this bulb is either green, yellow or orange light. That type of light is not primarily absorbed by the chlorophyll and peridinin pigments within the algae. The bulb does however emit significant amounts of violet and blue light which are primarily useable by the algae. This bulb could use a boost within its high energy blue part of the emission spectrum around 440 nm. Many aquarists have had success with the bulb and it is definitely useable. The very strong photon flux density emitted by the bulb helps to compensate for its spectral limitations. This bulb will moderately stimulate the blue, yellow and linked red fluorescing pocilloporin pigments. Green and red fluorescing pocilloporin will be strongly stimulated to fluoresce. A moderate amount of light emitted by this bulb can be absorbed by the pink pocilloporin pigment. The 400 and 250 watt versions of this bulb are both useable for shallow water stony corals. Many aquarists will use actinic fluorescents to help balance the green/yellow appearance of the bulb. It would be better to add blue light because the bulb already emits a significant amount of violet light.
probibly more info then you wanted but, it may give you an idea of the corals needs