XM Metal Halide HQI Double-ended Lamp - 20,000K - 250W Metal halide lamps of the same kind are different colors?Metal halide lamps operate by passing an el The metal halide lamp fires and then either burns dull or the arc extinguishes?Usually the ballast a Do I need a cover shield between the lamp and the aquarium?Metal halide lamps produce a large amount Can I operate a ballast and lamp together which are designed for different wattages?Each wattage lam