Complete Guide to Coral Tank Lighting
Comparing LED, T5, and metal halide lights for coral tanks: PAR values, spectrum selection, photoperiod settings, and budget recommendations for reef aquariums.
Key Takeaways
Comparing LED, T5, and metal halide lights for coral tanks: PAR values, spectrum selection, photoperiod settings, and budget recommendations for reef aquariums.
Lighting selection is one of the most critical issues for successful coral tank keeping, alongside water quality management. Most corals obtain energy through photosynthesis performed by symbiotic zooxanthellae living within their bodies. Without adequate light, zooxanthellae decline, causing corals to bleach and weaken.
This article systematically explains the fundamental knowledge for selecting lighting for coral tanks, the characteristics of different lighting fixture types, how to consider light intensity and spectrum, and practical setup methods.
Basic Light Requirements for Corals
Light required by corals has two elements: "intensity (light quantity)" and "color (spectrum)."
Light Intensity (PAR Value): PAR (Photosynthetically Active Radiation) is an indicator of photosynthetically active radiation, and measured values from a PAR meter serve as a reference in coral keeping. General guidelines are as follows:
- Soft Corals: PAR 50–150
- LPS (Large Polyp Scleractinian Corals): PAR 100–250
- SPS (Small Polyp Scleractinian Corals): PAR 200–450 or higher
Even within the same tank, PAR values change significantly depending on the height at which corals are placed. Therefore, the convention is to position SPS corals that require high light intensity in the upper sections and soft corals that need low light intensity in the lower sections.
Spectrum (Light Color): Zooxanthellae in corals utilize blue light (around 400–490 nm) most efficiently for photosynthesis. Therefore, coral tank lighting emphasizes a spectrum centered on blue light. On the other hand, red and orange light tend to promote algae growth, so they are typically used sparingly in coral tanks.
In terms of aesthetic beauty, blue and cyan light bring out the fluorescent pigments in corals and create vivid coloration. Many enthusiasts prefer blue-toned lighting because it achieves both photosynthetic efficiency and visual beauty.