PAR for Zoanthids (Zoas): Target Range and Placement
Zoanthids (zoas) and their Palythoa cousins are among the more forgiving corals on light, which is part of why they are a common first coral. They do best in low to moderate PAR, and they colour up better under stable light than under constant tweaking. These are the PAR (µmol/m²/s) ranges the reef hobby broadly converges on for zoanthids. Sources differ at the edges, so the numbers below are the span across several reef care guides rather than one fixed figure. Every range is sourced.
Target PAR for zoanthids
| Light level | PAR (µmol/m²/s) | Notes |
|---|---|---|
| Low | ~50–100 | Zoas survive but may stretch toward the light |
| Medium (ideal) | ~100–150 | The sweet spot most zoanthids colour up in |
| High | ~150–250 | Some varieties thrive here; watch for bleaching |
Guides put the practical band anywhere from about 50 to 250 PAR. The tighter “ideal” most keepers cite is roughly 75–150, with retailers stating the wider 50–150 or 75–250 depending on how much high-light tolerance they include. Aim for the middle first, then adjust based on how the colony responds.
Placement and acclimation
- Start low, move up. Place new zoanthids in a lower or mid-tank spot first, then move them higher over two to three weeks only if they need more light. A sudden jump in PAR causes light shock and can bleach or close the polyps.
- Watch the polyps. If zoas stretch or their stalks elongate reaching for light, they want more. If they stay closed or pale under strong light, they want less.
- Stable beats bright. Zoanthids reportedly hold better colour under consistent lighting than under frequent intensity changes, so favour stability over chasing the maximum the range allows.
- Flow interacts with light. Gentle, steady flow keeps polyps open and free of debris; too much flow makes them close regardless of light. Placement is a light and flow decision together.
Where zoas sit among other corals
Zoanthids are a soft coral for lighting purposes, in the same low-to-moderate band as mushrooms and leathers, and below LPS and SPS. For the full picture across coral groups, including per-genus detail, see PAR levels for SPS, LPS and soft corals.
Measuring PAR without a meter
If you do not own a quantum meter, you can approximate reef PAR from your fixture’s published PAR map corrected for depth. It is rough, and a phone lux app is particularly weak on blue-heavy reef spectra underwater. See estimating reef PAR without a meter for the method and its limits. These ranges are guidance, not law. Individual colonies acclimate to a band around these numbers, and spectrum, flow, and feeding all interact with light. Watch the coral.
Sources
- Zoanthid PAR range (75–250) and placement guidance: https://www.bulkreefsupply.com/content/post/coral-care-guide-zoanthids
- Zoanthid care, moderate-light PAR (about 50–150): https://www.extremecorals.com/blog/care-requirements-of-zoanthids-in-home-reef-aquariums.html
- Low / medium / high PAR bands for zoanthids: https://www.ewash.org/what-is-the-par-range-for-zoanthids