Reef Lighting PAR Calculator by Coral Type
Get the target PAR range for your coral category at coral placement depth. This tells you what your fixture needs to deliver there, not a universal number for the tank.
Your Coral
Target PAR at coral placement depth
100-250 µmol/m²/s
acclimate gradually toward the top of this range, don't jump straight to it
A mixed reef means different corals need different light. Place SPS (200-400) highest/closest to the fixture, LPS (100-250) mid-tank, and softies (50-150) in the shade of rockwork or lower placement.
Why depth isn't in the formula: There's no validated reef-specific formula for PAR loss per inch of water depth, since attenuation depends on your fixture's spectrum and your water clarity, not a universal constant. Instead, check your specific fixture's own published PAR map (most brands like AI and EcoTech publish PAR-vs-height charts) to confirm it can hit this target at your coral's actual placement depth, and always acclimate corals to new lighting gradually regardless of the number.