Metal
Halide aquarium lighting systems simulate natural
sunlight with point-source light from high intensity
discharge metal halide bulbs. Metal halides are available
in two main types, mogel base screw type bulbs and HQI
double ended bulbs. Screw type bulbs can be housed in
deluxe or retrofit lighting systems. Deluxe aquarium
lighting systems are complete hoods that surround the
metal halide bulb(s) along with any additional supplemental
lighting for placement on top of or hanging above the
aquarium. Retrofit aquarium lighting systems are generally
metal halide bulb(s) and socket(s) assemblies that can
be mounted to a reflector which is installed within an
existing wooden canopy above the aquarium. Double ended
HQI metal halide aquarium lighting systems utilize small,
double ended metal halide bulbs that are lacking the
UV protective shield. The HQI bulbs must be housed in
a deluxe hood or pendant that surrounds he bulb while
providing a UV protective glass lens. HQI metal halides
are not sold as retrofit kits because the UV protective
lens prevents your corals from exposure to damaging UV
radiation. Supplemental lighting found in metal halide
systems provide additional blue actinic light. The proper
lighting spectum as well as a dusk-to-dawn effect can
easily be achieved with the use of supplemental actinic
lights. Flourescent, VHO, power compact, T5 and even
metal halide lamps are used as supplemental lighting
for aquarium metal halide systems.
Metal halide bulbs are available in several
different Kelvins, or color tempertures. 6,500K bulbs are
a yellow-white color, 10,000K bulbs are a crisp pure white
color, 13,000K bulbs are white with a very slight blue
tint, 14,000K bulbs are white with a strong blue tint,
and 20,000K bulbs are a deep blue tint. Metal halide bulbs
come in several wattages from 70, 100, 150, 175, 250, 400,
and 1,000 watt.
Selecting the proper wattage metal halide
system depends upon the depth of the aquarium as well as
the type of corals beign kept in the aquarium. 150 and
175 watt systems can be used on aquariums from 16" to
20" depth for corals requiring medium to high light
levels and for aquariums from 18" to 30" for
medium to low light level corals. 250 watt systems provide
adequate lighting for 18" to 30" deep tanks with
corals that require medium to high light levels and for
aquariums that are 24" to 36" in depth with corals
that require low to medium light levels. 400 watt metal
halides provide the proper lighting for aquariums 24" to
36" with corals that require high light levels and
32" to 48" deep tanks with medium to low light
level corals. 1000 watt metal halides provide tremendous
lighting that is adequate for tanks 30" to 48" with
corals that require high to medium light levels and for
tanks that are 44" to 60" deep with corals that
require lower light levels.
The following manufacturers produce high
quality metal halide aquarium lighting equipment:
