Reef Tank Lighting & PAR: A Guide to Coral Coloration
Ask a room full of reefers why one tank's corals glow like neon while another's look brown and flat, and the conversation almost always lands on lighting. Light is the engine that drives coral growth and color, but more light isn't automatically better. At Tropical Treasures in Cheyenne, dialing in lighting is one of the most rewarding upgrades we help hobbyists make.
The key is understanding a single number, PAR, and how to match it to the corals you keep. Get that right, and you unlock the vivid colors that make reef tanks so addictive. Let's break it down.
What PAR actually means 💡
PAR stands for Photosynthetically Active Radiation, which is just the amount of usable light your corals receive for photosynthesis. Watts and lumens describe the bulb; PAR describes what actually reaches the coral. It's measured with a PAR meter, and many local clubs and shops, including ours, can help you take readings. Think of PAR as the difference between how bright a lamp looks and how much energy a plant on the windowsill really gets.
PAR targets by coral type 🪸
Different corals want different light. As a rough guide: soft corals and LPS are happy around 50-150 PAR, most LPS and easygoing SPS sit comfortably in the 100-200 range, and demanding SPS like Acropora often want 200-350+. Place lower-light corals on the sand and sides, and high-light corals up on the rockwork.
Spectrum and color 🌈
PAR controls how much energy corals get, but spectrum controls how they look and which colors pop. Reef corals evolved under blue-heavy ocean light, so a spectrum weighted toward blue and actinic not only fuels them but also makes their fluorescent pigments glow. That's why most reef tanks look so blue. A touch of white keeps the tank from looking purple to your eye, but the blues do the heavy lifting for coral coloration.
Acclimating corals to light ⏳
Even the right PAR will bleach a coral if you ramp up too fast. New corals and new lights both need a slow introduction. Start your photoperiod and intensity low, then raise them gradually over a few weeks. If a coral pales or browns, adjust its placement or your light's intensity before assuming something else is wrong.
Do you really need a PAR meter? 🤔
Not necessarily to start. A PAR meter is a fantastic tool, but you don't have to own one. Many shops and reef clubs lend them out, and manufacturers publish PAR maps for popular lights. If your corals are growing, holding color, and showing good polyp extension, your lighting is probably fine. Reach for a meter when you're chasing demanding SPS or troubleshooting a coral that won't color up. The corals themselves are your best meter once you learn to read them.
The bottom line 🐚
Great coral color comes from matching PAR and spectrum to your corals, then changing things slowly. Don't blast a new tank with max intensity and expect magic; build up over time and let the corals adapt. Want help choosing a light or taking a PAR reading? Visit Tropical Treasures or call 307-369-1118, and we'll point you in the right direction. Find more reef guides on our Tank Buddy Blog.