incorporate differently colored chips (e.g., white, red,
blue, green) in a single unit and provide separate driving
controls for each color. These LEDs allow adjustment of
each different color and fine-tuning of the appearance of
the light. Using more sophisticated controls can provide
the user with infinite possibilities for adjusting intensity
and color.
LEDs anD thE aquarist
The aim of this discussion so far has been to provide a basic understanding of how LED systems operate and what
impacts their operation and life span. Now we will focus
on the practical elements of LED lighting to assist aquarists in choosing and using LEDs for their aquariums.
Efficiency. Up to 200 lumens/watt may be
commercially available in the next few years,
and LEDs will have the highest lumens/watt
rating of any light source in the near future.
Even current-generation LEDs are capable of
providing more lumens/watt than fluorescent
and metal halide systems. LEDs provide light
comparable to that of a metal halide or fluorescent setup, but use less power, resulting in lower
electricity bills and “greener” reef systems.
Design freedom. LEDs have a fairly small
form factor or required design space, and hence
offer a wide variety of sizes and shapes, permit-ting aesthetic designs that are hard to achieve
with large metal halide reflectors and fluorescent lamps. LEDs can be packaged as spotlights,
strip lights, or combinations of different colors
of LEDs, providing the opportunity to be creative in lighting a reef aquarium.
Spotlights can be used to highlight certain
corals or areas of the reef. Blue strip lights can
replace the actinic fluorescents that are very
common in reef aquariums. Mixing differently
colored LEDs and using the dimming feature of
the drivers creates various lighting effects, such
as moonlight, dawn/dusk, and even cloud effects during the day, using a single luminaire
fixture and exploiting the controllability possible with built-in or wireless controllers.
Selective dimming of differently colored
LEDs allows the user to fine-tune the color and
achieve a wide range of color temperatures. The
picture at the top of page 47 shows the range of designs
of various LED fixtures available from Ecoxotic.
no heat or uV. Both metal halide and fluorescent
lighting generate infrared heat that warms the water column, often necessitating the use of a chiller to maintain
temperatures below 80°F. The cost of chillers and the
associated power usage can be a large component of the
setup and operational costs of a reef system.
As seen in the technical discussion, LEDs do not produce any infrared heat, so there is no additional transfer
of heat to the water and chillers are not required. On the
other hand, using LEDs could necessitate the addition of
a heater, depending on the ambient temperature. LEDs
do not generate any UV light unless specific UV LEDs
are used.
Long life and low maintenance. The life span typically claimed for LEDs (where they produce 70 percent
of the initial light) is around 50,000 hours. While this
may be true under ideal conditions, a typical LED fixture
often has a shorter life, depending on the quality of the
system components, the system design, and the manufacturing quality. Even if we assume a more conservative estimate of 60–70 percent of the figure claimed, this
means that a well-designed LED system could be used
The author’s 35-gallon (132-L) nano tank, which uses the
Panorama LED from Ecoxotic.
for five to seven years without having to change bulbs.
This would represent a significant cost savings, given
that most reef aquarists change fluorescent lamps every
6 to 12 months and metal halides every 9 to 12 months.
While all these advantages are significant in their
own right, they are beside the point if the LEDs fail to
provide the light your corals need. The question is, how
much light do corals actually need? Based on the experiences of many hobbyists over years of successful reefkeeping, we know that corals can adapt to and thrive in a
