AQUALITE™ SPECTRAL DISTRIBUTION

Spectral Distribution
Wavelength theory provides a graphical representation of radiant energy and the electromagnetic spectrum. The preferred unit of wavelength for the visible and ultraviolet (UV) regions of the spectrum is the nanometer (nm).
UVC = 100–280nm: Most harmful and used in sterilization to kill biological organisms.
UVB = 280–315nm: Harmful and causes sunburn, skin cancer, and eye damage.
UVA = 315–400nm: Longer wavelength and less energy than other UV. It is the least harmful but still can be damaging.
Visible Light = 380–780nm

What about the UV? UVC and UVB in excessive amounts can be detrimental to fish and corals; However, UV light does occur naturally in sunlight which in balanced amounts is not necessarily harmful. Studies have found that the majority of coral reef fish produce mucus that absorbs harmful UVB rays. Corals also have developed a natural pigmentation as a protection from UV. Metal halide lamps produce UV light which can be significantly filtered by fixture glass and water depth. USHIO’s Aqualite™ metal halide lamps are balanced to reduce excessive amounts of UV light for your reef system.

PAR (Photosynthetically Available Radiation):
A measurement used to help determine the photosynthetic amount of light needed by corals and plant life. Photosynthesis in corals utilizes energy between the (blue) 400nm wavelengths and (red) 700nm wavelengths.

Aqualite™ 10,000K lamps produce the ideal balance of blue, white and red light in the spectrum to simulate daylight in the water. Our Aqualite™ lamps reduce the green light, a spectrum which can promote the growth of the “bad” algae that grows on corals.


Fixture Glass?
USHIO recommends the use of tempered safety glass on any fixtures using our Aqualite™ metal halide lamps. The safety glass not only reduces some UV, but also extends the life of your lamps and sockets by protecting them from salt water corrosion. UV protective glass is required for any architectural use of Aqualite™ metal halide lamps where people are directly exposed to the light.

 

Correlated Color Temperature Measured in degrees of Kelvin (K), color temperature is the absolute temperature of a blackbody radiator resembling that of the light source. Color Temperature can be used as a general rule of thumb to measure the appearance of “warmth” or “coolness” of a light source. It does have it’s limitations since lamps with the same color temperature rating will not often look the same between manufacturers. Other measurements such as CRI and spectral distribution should be considered when choosing a light source for your aquarium.

Household incandescent lighting that appears warm and yellow is approximately 2,700K. Outdoor daylight is approximately 5,600-6,000K. Aqualite™ 10,000K lamps approximate equatorial daylight at 5 meters of ocean depth. Aqualite™ 14,000K and 20,000K+ lamps are slightly bluer in appearance, simulating deeper water environments, ideal lighting for invertebrates such as lobsters and jellyfish. These lamps are also used in nigh time simulations.

 

CRI or Color Rendering Index CRI is an internationally accepted system to measure the capability of a light source to render color naturally. The closer the number is to 100 the closer that light source is rendering color like natural daylight. Fish, coral and plant life will appear much more true to life under higher CRI light sources. Luminous Flux Measured in Lumens is an industry standard for measuring the visible light output from the lamp.

Operating/Burn Position
The operating position of the lamp is specified to provide the proper light output and color. Changing the lamp operating position can change the thermal properties of the arc tube during operation causing some metals or salts to drop out of the arc stream and thus changing the color of the lamp.
 

Lamp Life The median life of metal halide lamps is statistically determined under controlled conditions on a 11 hours on, 1 hour off, cycle. Environmental factors including the lamp housing, reflector, power supply, and lamp cooling will affect lamp life considerably. All metal halide lamps degrade in light output and may shift in color over time. Inferior lamps are easy to spot since they significantly shift in color and drop off rapidly in output. The lamp life rating between different manufacturers may be the same on paper but performance over the life of the lamp will tell you your true cost of ownership.

USHIO Aqualite™ metal halide lamps utilize proprietary rare-earth mixtures to provide the most consistent lamp color over the entire lifetime of that lamp. Our arc tube forming process and coatings ensure that light degradation levels are kept to a minimum. For the best health of your aquarium and reef system, it is recommended that you schedule regular lamp changes depending upon your timing cycles and rated
lamp life. It is normal for metal halide lamps to stabilize in color and output within 100 hours of “burn in” operation.

Brand new lamps will always produce more light than lamps near their end of life. Your corals and fish will need time to adjust to the higher light levels. It is recommended that when a lamp is first replaced, that you first raise the light fixture and then lower it as the lamp ages.


Timing Cycles
For the health of your fish and reef systems the lighting system should be turned on at least 12 hours per day. Check with marine biology sources to determine the proper amount of daylight
hours needed for your specific species.
 

Ballasts and Power Supplies
It is extremely critical to match the proper ANSI coded lamp to the ANSI coded ballast. Failure to do so will cause improper lamp ignition, poor color and spectral performance, and short life.

For example: USHIO’s 175W Aqualite™ is a pulse start lamp. Pulse start type lamps may ignite and work just fine on a probe start ballast for a few months; however, as the lamp ages, the electrodes erode and
higher voltage is needed to start the lamp. The open circuit voltage provided by probe start ballasts is not sufficient to ignite a pulse start lamp. Pulse start lamps like our 175W Aqualite™ always require an
ignitor to keep the lamp starting throughout its life cycle.