Aquarium Lighting: PAR, Spectrum & Stability

Aqua Ultraviolet

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Aquarium lighting is not only about buying the most powerful fixture or copying someone else’s settings. The best setup depends on your tank depth, coral type, aquascape, and how evenly the light reaches every area.
PAR is useful, but do not focus only on the highest reading directly under the light. Check the top, middle, bottom, sides, and shaded areas of the tank. Good coverage is often more important than creating one very high-PAR hotspot.
For most mixed reefs, a practical starting point is:
  • Soft corals: around 50–100 PAR
  • Many LPS: around 75–175 PAR
  • SPS upper areas: around 200–350+ PAR
A blue-heavy spectrum is popular because it enhances coral fluorescence, but adding some white can make fish and corals look more natural during daytime viewing.
Most importantly, make changes slowly. A sudden increase in intensity or a new lighting schedule can cause bleaching or fading, even if the PAR number seems “correct.” Stable lighting, gradual acclimation, and observing coral response will usually give better results than constantly changing settings.
What light are you using, and do you prioritize PAR, spectrum, or coverage?
 

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