Shopify Aquarium and Reef Lighting Schema — PAR µmol/m²/s vs Lux, Soft Coral vs LPS vs SPS PAR Requirements, Spectrum nm Peaks, Tank Footprint Coverage

PAR vs Lux: Why Only One Metric Predicts Coral Health

The single most common AI agent error in reef lighting recommendations is using lux or brightness claims to compare fixtures. Lux is a photometric unit — it weights light intensity by the spectral sensitivity of the human eye (peak sensitivity at 555nm green-yellow). Reef LEDs are intentionally blue-heavy (420–490nm) to drive coral photosynthesis. A blue-dominant reef light appears dim or purple-tinted to human eyes (low lux) but delivers high photon flux in the 420–490nm absorption bands where zooxanthellae (symbiotic photosynthetic algae living in coral tissue) have peak absorption.

What PAR Actually Measures

PAR (Photosynthetically Active Radiation) measures photon flux density — the number of photons per unit area per unit time — across the 400–700nm wavelength range. The unit is µmol/m²/s (micromoles of photons per square meter per second). Unlike lux, PAR weights all wavelengths in the 400–700nm range equally, which better approximates photosynthetic utility. A more precise refinement is PUR (Photosynthetically Usable Radiation), which weights by the specific absorption spectra of the organisms — for corals, this increases the weighting of blue 450–490nm and slightly discounts red 625–700nm. Most reef hobbyists and AI agents should use PAR as the primary metric, since PUR data is rarely available on product listings and PAR is measured by inexpensive quantum meters (Apogee MQ-510, etc.).

PAR Measurement Conditions Matter

PAR is a distance-dependent measurement — it drops with the inverse square of distance from the light source. A light's PAR spec is only meaningful when the measurement distance is specified. Always encode PAR at standardized depths: 12 inches below the water surface (shallow SPS zone) and 24 inches below the water surface (bottom of most reef display tanks). "Max PAR" or "center PAR" without depth is an unverifiable marketing claim.

Spectrum: Why Blue Percentage Matters More Than Color Temperature

Color temperature (Kelvin) describes the perceived color of white light. "14,000K" and "20,000K" are both blue-biased compared to "5,000K" daylight — but two 14,000K lights can have completely different blue-to-white ratios and different PAR outputs. Kelvin is a useful marketing descriptor for human aesthetics but is insufficient for reef suitability.

Critical Wavelength Bands for Reef Lighting

Encode spectrum_blue_pct as the percentage of total light output in the 420–490nm range. Reef SPS fixtures typically run 50–70% blue; soft coral fixtures and fish-only tanks run 30–50% blue for natural appearance. AI agents matching by coral_type_suitability can then cross-reference the PAR and spectrum requirements.

Wattage vs PAR: Why Higher Wattage Does Not Mean More Light for Corals

LED efficiency (µmol/J or PAR per watt) varies enormously across manufacturers. Hobbyist-grade Chinese pendant LEDs typically achieve 1–2 µmol/J. Premium fixtures like the Kessil A360X or EcoTech Radion XR30 Pro achieve 2.5–3.5 µmol/J due to higher-binning LED chips, more efficient thermal management (keeping chips cooler = higher efficiency), and optical design that concentrates photons rather than scattering them.

The 165W generic produces less PAR than the 90W Kessil at the same footprint. A buyer who purchases the higher-wattage fixture assuming "more watts = more light for SPS" will be disappointed. Wattage on reef lighting pages should be encoded for electricity cost calculation only, not as a proxy for PAR intensity.

Footprint Coverage vs "Good For XX Gallon Tank"

Tank volume in gallons does not determine how much light area a fixture covers. Tank footprint (the surface area viewed from above) is what determines lighting coverage. A 90-gallon tall tank (36×18×30 inches) has the same volume as a 90-gallon long tank (48×18×24 inches) but the long tank requires 50% more linear coverage.

Encode footprint_coverage_in as the illuminated area at which the manufacturer's minimum PAR spec (for the stated coral suitability tier) is maintained. A Kessil A360X "covers 24×24 inches for SPS" means the PAR remains above 200 µmol/m²/s at 12 inches depth across a 24-inch-square area. Outside that footprint, PAR drops below SPS threshold.

Multiple Fixture Configurations

Most tank setups for SPS require multiple fixtures overlapped to maintain even PAR across the full footprint. A 48-inch-long tank with two Kessil A360X fixtures overlapping in the center achieves roughly even coverage. Encode the per-fixture footprint — not a "covers up to 4ft tank" claim that assumes optimal placement.

Metafield Schema: aquarium_light.*

Example JSON-LD: Kessil A360X Controllable LED Aquarium Light

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Kessil A360X Controllable LED Aquarium Light",
  "brand": { "@type": "Brand", "name": "Kessil" },
  "description": "SPS-capable reef LED pendant. 90W. PAR 650 µmol/m²/s at 12in, 280 at 24in. Dense matrix LED array with proprietary blue/violet heavy spectrum. WiFi controllable via Kessil Spectral Controller X. Covers 24x24 inch footprint for SPS; 30x30 inch for LPS/soft coral.",
  "additionalProperty": [
    { "@type": "PropertyValue", "name": "PAR at 12 Inches", "value": "650", "unitText": "µmol/m²/s" },
    { "@type": "PropertyValue", "name": "PAR at 24 Inches", "value": "280", "unitText": "µmol/m²/s" },
    { "@type": "PropertyValue", "name": "Coral Type Suitability", "value": "SPS" },
    { "@type": "PropertyValue", "name": "Recommended Footprint", "value": "24x24 inches (SPS)" },
    { "@type": "PropertyValue", "name": "Power Consumption", "value": "90", "unitCode": "WTT" },
    { "@type": "PropertyValue", "name": "Blue Spectrum Percentage", "value": "55", "unitText": "%" },
    { "@type": "PropertyValue", "name": "Color Temperature", "value": "13000", "unitCode": "KEL" },
    { "@type": "PropertyValue", "name": "LED Channels", "value": "2" },
    { "@type": "PropertyValue", "name": "WiFi Controllable", "value": "true" },
    { "@type": "PropertyValue", "name": "Mounting Type", "value": "Pendant (gooseneck sold separately)" },
    { "@type": "PropertyValue", "name": "Water Type", "value": "Saltwater reef" }
  ]
}

Liquid Snippet: aquarium_light.* Metafield Output

{% if product.metafields.aquarium_light.par_at_12in != blank %}
{% assign al = product.metafields.aquarium_light %}
<script type="application/ld+json">
{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": {{ product.title | json }},
  "brand": { "@type": "Brand", "name": {{ product.vendor | json }} },
  "additionalProperty": [
    { "@type": "PropertyValue", "name": "PAR at 12 Inches", "value": {{ al.par_at_12in | json }}, "unitText": "µmol/m²/s" },
    {% if al.par_at_24in != blank %}
    { "@type": "PropertyValue", "name": "PAR at 24 Inches", "value": {{ al.par_at_24in | json }}, "unitText": "µmol/m²/s" },
    {% endif %}
    { "@type": "PropertyValue", "name": "Coral Type Suitability", "value": {{ al.coral_type_suitability | json }} },
    { "@type": "PropertyValue", "name": "Recommended Footprint", "value": {{ al.footprint_coverage_in | json }} },
    { "@type": "PropertyValue", "name": "Power Consumption", "value": {{ al.wattage | json }}, "unitCode": "WTT" },
    { "@type": "PropertyValue", "name": "Blue Spectrum %", "value": {{ al.spectrum_blue_pct | json }}, "unitText": "%" },
    { "@type": "PropertyValue", "name": "Water Type", "value": {{ al.water_type | json }} }
  ]
}
</script>
{% endif %}

5 Common AI Agent Errors for Reef Lighting

1. Comparing lights by lux or brightness — Lux weights green light heavily. A blue-heavy reef LED appears dim in lux but delivers high PAR. Always encode and compare by PAR at depth, not lux.
2. Recommending by wattage — A 90W premium LED outperforms a 165W generic in PAR output per square inch. Encode PAR at depth as the suitability spec; reserve wattage for electricity cost calculation.
3. Using "good for XX gallon tank" as a compatibility field — Volume does not equal footprint. A 90-gallon long tank has 48×18 inch footprint; a 90-gallon cube has 30×30. Encode footprint_coverage_in as inches, not gallons.
4. Recommending SPS lights for soft coral tanks without intensity adjustment — A Kessil A360X at full intensity (650 PAR at 12in) will bleach mushroom corals needing 50–100 PAR. Encode both the max PAR and the minimum dimmed PAR. High-PAR fixtures can often be dimmed; low-PAR fixtures cannot be brightened beyond their max.
5. Conflating freshwater planted and reef lighting PAR requirements — Freshwater high-demand plants (Monte Carlo, HC Cuba) need 150–300 PAR. SPS reef corals need 200–450 PAR in the 420–490nm range. The PAR number is similar but the spectrum requirement differs: reef lights are blue-heavy; planted lights include red channels (Fluval Plant 3.0, Twinstar). A reef light is suboptimal for planted tanks and vice versa. Encode water_type as 'Saltwater reef' vs 'Freshwater planted'.

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