Free reef tank tool
Coral PAR Calculator
Check whether your reef tank lighting is likely too low, too high, or in a typical starting range for your coral.
How the Coral PAR Calculator Works
This coral PAR calculator compares a measured or estimated PAR number with typical starting ranges for common reef aquarium corals. If you know the measured PAR at the coral location, enter that value and select the coral. The tool then checks whether the number is likely too low, in a typical range, near an edge, or likely too high for that coral profile. If you do not know PAR, the reef tank PAR calculator estimates light intensity from reef light strength, tank depth, aquascape zone, and shading.
Measured PAR is always better than estimated PAR. Estimate mode is meant to help you reason about a likely lighting zone, not to replace a PAR meter. The result is an educational starting point: verify with trusted reef references, consider the coral's history, and observe the coral after any lighting change.
What Is PAR in a Reef Tank?
PAR means photosynthetically active radiation. In reef aquariums, hobbyists use PAR to discuss the light intensity available to photosynthetic corals and their symbiotic algae. PAR is usually measured with a PAR meter at the exact place where the coral sits. That location matters because light drops with depth, rockwork can create shadows, and a coral under an overhang can receive much less light than one only a few inches away.
Typical PAR Ranges for Soft Corals, LPS and SPS
Soft coral PAR requirements often start around 50-150 PAR. LPS coral PAR requirements often start around 80-200 PAR. SPS PAR requirements often start around 200-400 PAR. These are not exact rules. Individual species, color morphs, tank history, nutrients, water clarity, and previous acclimation all affect how a coral responds.
Soft Coral PAR
Zoanthids, mushrooms, leathers, and Green Star Polyps are often kept in lower to moderate light. Many soft corals are adaptable, but sudden changes can still cause closed polyps, shrinking, or color changes. Mushroom corals often prefer lower light, while some zoanthids and leathers may tolerate more light after slow acclimation.
LPS Coral PAR
Torch coral PAR, hammer coral PAR, frogspawn, Duncan, Favia, chalice, and Goniopora ranges are usually moderate compared with many SPS corals. Fleshy LPS can react poorly when moved into too much light too fast. Retraction, pale tissue, or recession can be signs to slow down, but light is only one possible cause.
SPS Coral PAR
Acropora PAR is commonly higher than most soft coral and LPS starting ranges. Montipora and Birdsnest also often need moderate to high PAR. SPS corals usually need strong turbulent flow and stable alkalinity, nutrients, salinity, and temperature in addition to suitable light. High PAR by itself does not guarantee growth.
Why Estimated PAR Is Not the Same as Measured PAR
A reef tank lighting calculator can only approximate what is happening in the aquarium. Fixture mounting height, LED lens angle, spectrum, water clarity, surface agitation, glass lids, rock shadows, coral height, and channel settings all change the real PAR at the coral. Two tanks with the same light fixture can have very different PAR maps. When possible, borrow, rent, or use a PAR meter before making major changes, especially for Acropora or other high-light SPS.
How to Adjust Coral Lighting Safely
Make light changes gradually. Raise intensity in small steps, move coral upward slowly, or use partial shade while the coral adapts. Avoid moving a stressed coral every few hours because repeated handling can add more stress than the original placement. Watch extension, color, tissue condition, and feeding response over days, not minutes. Also check flow, nutrients, alkalinity, pests, and neighbor aggression before assuming PAR is the only issue.
What If You Don't Know the Coral ID?
PAR needs depend heavily on coral type. Similar-looking corals can have different lighting tolerance, and retail names are sometimes broad or inconsistent. If you are unsure whether a coral is a torch, hammer, frogspawn, chalice, Favia, Goniopora, soft coral, or SPS, use a conservative temporary placement first. Coral Identifier can scan a photo and provide likely coral matches, then you can verify those matches with trusted reef references before changing lighting or placement.
FAQ
Use these answers as cautious starting points. A PAR meter, coral ID verification, and direct coral observation are still important.
What PAR do soft corals need?
Many soft corals use a typical starting range around 50-150 PAR, though mushrooms may prefer lower light and some zoanthids or leathers can adapt higher. Treat this as an estimated starting range and observe the coral after changes.
What PAR do LPS corals need?
Many LPS corals are started around 80-200 PAR. Torch, hammer, frogspawn, Duncan, Favia, chalice, and Goniopora can react poorly to sudden light increases, so verify the coral and acclimate gradually.
What PAR do SPS corals need?
SPS corals often start around 200-400 PAR, with Acropora commonly kept toward the higher end. SPS care also depends on strong flow, stable alkalinity, nutrients, and tank maturity.
How much PAR does a Torch Coral need?
A Torch Coral is often started around 100-180 PAR, with caution below about 70 and above about 220. Individual specimens and acclimation history matter, so avoid sudden jumps.
How much PAR does a Hammer Coral need?
A Hammer Coral is often started around 80-160 PAR. Some may adapt outside that range, but intense light without acclimation can cause retraction or pale tissue.
How much PAR do Zoanthids need?
Zoanthids often start around 60-150 PAR. Different varieties can respond differently, so use coral behavior and trusted references rather than assuming color alone tells you the care requirement.
Is estimated PAR accurate?
Estimated PAR is only a rough planning aid. Fixture mounting height, lens angle, water clarity, rock shadows, surface movement, and light settings can change the actual PAR at the coral.
Do I need a PAR meter?
A PAR meter is strongly preferred when placing high-light SPS, changing lights, or troubleshooting stressed coral. This calculator does not replace measured PAR.
Can too much PAR bleach coral?
Too much light, or a light increase made too quickly, can contribute to bleaching, paling, tissue recession, or retraction. Chemistry, flow, pests, and handling stress can also be involved.
Should I move my coral if PAR is too low or too high?
Do not rush repeated moves. If the coral is not in immediate danger, adjust gradually, observe the response, and verify the coral ID and overall tank conditions before making major changes.
Coral Identifier
Scan first when the coral ID is uncertain.
Coral Identifier gives likely coral matches from photos. Use it as a starting point, then verify with trusted reef references before making lighting or placement changes.