Radium 400W SE Metal Halide Bulb (20000K)
Radium metal halide bulbs are German made and offer excellent coloration and good intensity.
They are crisp-white with a strong blue tint and bring out the fluorescent pigments in corals nicely.
Fluorescent supplementation is usually not necessary, but can be used for added intensity and to simulate dawn and dusk.
An electronic ballast, magnetic pulse-start ballast or magnetic HQI ballast is required to ignite this bulb. This bulb is white with a blue tint on a magnetic HQI ballast.
It will burn more blue on an electronic ballast.