Marine aquariums have achieved a new level of beauty—thanks in part to the widening use of visually appealing corals. Much of the progress in the field has to do with technical advances that have made it easier to cultivate corals in a tank. Filtration methods have seen significant improvement, as have measurement and dosing techniques—and aquarium lighting.
As most reef-tank owners are aware, proper lighting is key to maintaining a marine aquarium. First, light stimulates the growth of corals, which host tiny photosynthesizing creatures known as zooxanthellae. In addition, light is important for creating a photoperiod—a day/night simulation—in the aquarium. That stimulates the natural activity of corals and other aquarium life.
Reefers need to keep three factors in mind: light intensity (irradiance), spectral distribution, and light distribution. When it comes to coral, for example, sufficient light intensity is required not only to stimulate photosynthesis and growth but also to support coloration.1 Corals of the genus Acropora, for example, need an irradiance of at least 700 μmol photons m-2 s-1 as photosynthetically active radiation to fully saturate host pigmentation.2
In terms of spectrum, enough blue radiation is required to support healthy coral growth and chlorophyll synthesis.3 In addition, visualizing the colors of the entire range of aquarium life requires that a given spectrum contains a broad spectrum of wavelengths. The “ideal” light spectrum for the average marine aquarium is continuous, with most energetic content around the region of 400-500nm, to ensure light that properly resembles the light to which coral is exposed in nature. That spectrum compares to the one you’d find at a seawater depth of approximately 10 meters, where all colors remain present, but where there’s less red and orange. (Seawater selectively attenuates sunlight,4 more effectively filtering out longer-wavelength light.)
Finally, reefers need a light source offering a homogeneous distribution over different surfaces. Such a distribution is beneficial to an aquarium’s inhabitants as well as aesthetically pleasing. Some reefers also desire a dynamic shimmer effect, which mimics a sunny day on a coral reef.
The Philips CoralCare LED aquarium lighting solution is a great choice when it comes to all three of these factors—and more.
Designed as the perfect replacement for the conventional T5 luminaires that used to light marine aquariums, Philips CoralCare provides a range of benefits:
A field test compared how the CoralCare unit performed as a light source for marine aquaria, and particularly for corals, with how traditional T5 luminaires performed. Researchers divided an aquarium into two sections using a PVC separator (to prevent crossover effects). On one side of the separator, they placed two 190W CoralCare units above a 490L aquarium (200 x 70 x 35 cm in size). On the other side, they placed two T5 reference luminaires (ATI Sunpower, 6x54W, both of them dimmable).
They evaluated the performances of the light sources by measuring the specific growth rate of each coral species, as well as by subjective photographic analysis of their morphology and color over a six-month period. They found that Philips CoralCare LED unit delivers results that compare extremely well to those of conventional T5 technology—yet at 30 percent higher wall-plug efficiency. Long-term use by aquarists is likely to substantiate the report’s results in terms of coral health, coloration, morphology and growth rates.
In conclusion, the CoralCare unit is the first LED-based product that rivals T5 lighting, the current market standard. What’s more, it provides similar results much more efficiently. The CoralCare LED unit also represents a significant step forward in terms of technology and controllability.
LED lighting has transformed how we light our city streets and our work and living spaces. Now it’s also improving lighting in more specialized fields of endeavor—such as the art of keeping a healthy, vibrantly beautiful marine aquarium.
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References
1. D’Angelo C., Denzel A., Vogt A., Matz MV., Oswald F., et al. (2008). Blue light regulation of host pigment in reef–building corals. Marine Ecology Progress Series 364: 97–106.
Muscatine L. (1990). The role of symbiotic algae in carbon and energy flux in reef corals, 75–87. In: Dubinsky Z (Ed), Coral reefs: ecosystems of the world 25. Elsevier, Amsterdam, The Netherlands.
Muscatine L., McCloskey LR., Marian RE. (1981). Estimating the daily contribution of carbon from zooxanthellae to coral animal respiration. Limnology and Oceanography 26: 601–611.
2. D’Angelo C., Denzel A., Vogt A., Matz MV., Oswald F., et al. (2008). Blue light regulation of host pigment in reef–building corals. Marine Ecology Progress Series 364: 97–106.
3. Kinzie III RA., Hunter T. (1987). Effect of light quality on photosynthesis of the reef coral Montipora verrucosa. Marine Biology 94: 95–109.
Kinzie III RA., Jokiel PL., York R. (1984). Effects of light of altered spectral composition on coral zooxanthellae associations and on zooxanthellae in vitro. Marine Biology 78: 239–248.
Wang L–H., Liu Y–H., Ju Y–M., Hsiao Y–Y., Fang L–S., et al. (2008). Cell cycle propagation is driven by light–dark stimulation in a cultured symbiotic dinoflagellate isolated from corals. Coral Reefs 27: 823–835.
Wijgerde T, van Melis A, Silva CIF, Leal MC, Vogels V, Mutter M, Osinga R (2014) Red light represses the photophysiology of the scleractinian coral Stylophora pistillata. PLoS ONE 9(3): e92781. DOI: 10.1371/journal.pone.0092781
4. Mass T., Kline DI., Roopin M., Veal CJ., Cohen S., Iluz D., Levy O. (2010). The spectral quality of light is a key driver of photosynthesis and photoadaptation in Stylophora pistillata colonies from different depths in the Red Sea. Journal of Experimental Biology 213: 4084–4091.
