Understanding PAR, PUR, and Spectrum in Reef LED Lighting

Modern reef LED lighting has revolutionized coral husbandry. PAR (Photosynthetically Active Radiation) measures the quantity of light available for photosynthesis between 400-700nm. PUR (Photosynthetically Usable Radiation) is more relevant as it measures only the wavelengths corals actually use.\n\nKey considerations:\n- SPS corals typically need 250-350 PAR at the surface\n- LPS corals thrive at 100-200 PAR\n- Soft corals do well at 50-150 PAR\n- Blue spectrum (420-480nm) drives fluorescence and photosynthesis\n- UV (380-420nm) enhances coral coloration\n\nTop LED fixtures in 2025-2026 include the Ecotech Radion G6, AI Hydra 64, Kessil A500X, and Orphek Atlantik. The trend is toward fuller spectrum coverage with individual channel control.\n\nMounting height affects spread and intensity. Use a PAR meter (Apogee MQ-510) to map your tank and adjust accordingly. Many reefers run a 10-12 hour photoperiod with a gradual ramp up/down simulating sunrise and sunset.