Lighting can make or break a reef aquarium. The right spectrum and intensity bring out vivid colors, support coral growth, and create that shimmering reef look we all love. This reef lighting guide will walk you through the essentials so you can choose, tune, and maintain lighting that keeps your corals healthy and thriving.

Understanding Reef Lighting Basics

Corals host symbiotic zooxanthellae algae that rely on light for photosynthesis. In reef tanks, we try to mimic the light conditions found on natural reefs—strong, blue-heavy light with stable intensity throughout the day.

Spectrum: Why Blue Is King

Most reef aquariums do best with a spectrum that emphasizes blue and violet wavelengths (around 400–500 nm). These wavelengths:

• Penetrate water more efficiently than warm white light
• Support photosynthesis for most coral species
• Enhance fluorescence and color pop

White light still has a place, especially for a more natural daylight look, but the backbone of a reef lighting schedule is usually blue-heavy.

Intensity and PAR Targets

Rather than thinking in watts, reef hobbyists use PAR (Photosynthetically Active Radiation) to measure usable light. Rough guidelines:

• Soft corals & zoanthids: ~50–150 PAR
• LPS corals: ~75–200 PAR
• SPS corals: ~200–350+ PAR

These are ballpark numbers; each species has its own comfort zone. When in doubt, start on the lower end and increase light slowly over weeks.

Tip: If you don’t own a PAR meter, watch your corals closely. Bleaching, receding tissue, or overly closed polyps can be signs of too much light too quickly.

Choosing the Right Reef Light

Modern reefers have three main options: LED, T5 fluorescent, and metal halide. Most hobbyists now prefer LED fixtures for their efficiency and control.

LED Pros for Reef Tanks

• Adjustable spectrum and intensity via app or controller
• Lower power consumption and less heat
• Longer lifespan and minimal bulb changes

When comparing LED units, look for:

• Even spread to avoid harsh hotspots and shadows
• Dedicated UV/violet, royal blue, and blue channels
• Proven track record on similar-sized reef tanks

For help sizing equipment to your aquarium, check out our reef tank setup checklist, which covers matching lights to tank dimensions and coral plans.

Programming Your Reef Lighting Schedule

A stable, predictable photoperiod is just as important as the light itself. Many reef keepers aim for 8–10 hours of strong light, with gentle ramps at the beginning and end of the day.

Sample Daily Lighting Schedule

• Morning (1–2 hours): Low-intensity blue ramp up
• Midday (6–8 hours): Peak intensity with blue-heavy spectrum
• Evening (1–2 hours): Gradual ramp down to blues, then off

Use acclimation modes when upgrading lights or increasing intensity. Many modern fixtures can automatically ramp up over several weeks to protect your corals from shock.

Tip: Combine lighting changes with good nutrient control and stable parameters. Our reef water parameters guide explains how stability in chemistry and light go hand in hand.

Finally, don’t forget maintenance: clean salt creep and dust from lenses and splash guards monthly to maintain output and clarity. A dirty lens can significantly reduce PAR over time.

With the right spectrum, intensity, and schedule, your reef lighting becomes more than just hardware—it becomes a powerful tool for coral health and color. Dial it in patiently, observe your tank’s response, and you’ll be rewarded with a vibrant, thriving reef. For a deeper dive into building a complete system around your lighting, visit our beginner reef aquarium guide and connect the dots between equipment, livestock, and long-term success.