1. Light Spectrum — Wavelengths & Ratios
Why Spectrum Matters
Cannabis uses photosynthetically active radiation (PAR) from 400–700 nm, but not all wavelengths are equally effective. Two key photoreceptor families drive growth and morphology:
- Chlorophyll a/b — absorption peaks at ~430 nm (blue) and ~662 nm (red)
- Cryptochromes & Phytochromes — control photomorphogenesis: stretch, branching, flowering timing
Vegetative Stage Spectrum
| Parameter | Recommendation | Rationale |
|---|
| Dominant spectrum | Cool-white ~5000K–6500K | High blue (440–470 nm) keeps internodes tight, prevents stretch |
| Blue (400–500 nm) | 25–35% of total PPF | Drives chlorophyll b, stomatal opening, compact morphology |
| Green (500–600 nm) | 20–25% of total PPF | Penetrates deeper into canopy, improves lower-leaf photosynthesis |
| Red (600–700 nm) | 35–45% of total PPF | Core photosynthetic driver; balance against blue to prevent stretch |
| Far-red (700–750 nm) | 5–10% of total PPF (optional) | Emerson enhancement effect — boosts PSII/PSI synergy; can increase node spacing slightly |
| UV (380–400 nm) | 0–1% (optional) | May increase secondary metabolite production; use sparingly |
Key ratio: In veg, target a R:B (red:blue) ratio of roughly 1.2–1.5:1 (slightly more red than blue but still heavy on blue compared to flower).
Flowering Stage Spectrum
| Parameter | Recommendation | Rationale |
|---|
| Dominant spectrum | Warm-white ~2700K–3500K | Higher red ratio triggers flowering response, deep canopy penetration |
| Blue (400–500 nm) | 10–15% of total PPF | Maintains resin production and trichome integrity; minimum needed |
| Green (500–600 nm) | 15–20% of total PPF | Critical for lower canopy penetration |
| Red (600–700 nm) | 50–65% of total PPF | Maximizes photosynthetic efficiency during flower development |
| Deep red (660 nm) | 15–25% of total PPF | Aligns precisely with chlorophyll a absorption peak; drives bud density |
| Far-red (700–750 nm) | 8–15% of total PPF | Critical: Phytochrome conversion (Pfr→Pr) accelerates flowering; Emerson effect boosts yield 5–15% |
| UV (380–400 nm) | 0.5–2% (optional) | May increase THC/CBD % via stress response; use cautiously to avoid photobleaching |
Key ratio: In flower, target a R:B ratio of roughly 4–6:1 (heavily red-shifted).
How the Eclipse 328 Delivers
The Eclipse 328 combines:
- Samsung LM301H EVO — white LEDs with a broad 400–750 nm distribution (typically ~3000K–5000K depending on binning)
- OSRAM deep red (660 nm) — narrow-band 660 nm diodes that hit the chlorophyll a absorption peak exactly
- Smart WiFi control — allows spectrum tuning via percentage dimming per channel (if multi-channel), or overall intensity ramping over the day
Recommendation for Eclipse 328 users:
- Run full-spectrum white at ~5000K for veg, supplementing with 660 nm deep red at 20–30% total power
- Switch to ~3000K white for flower, bump the OSRAM 660 nm deep red to 50–80% of total power, and — if possible — add far-red (~730 nm) LEDs, or use the onboard far-red if the fixture includes it (verify spec sheet)
- Use the sunrise/sunset dimming (WiFi app) to include 15 min far-red ramps at lights-on/lights-off — this triggers the Emerson effect without stressing plants
2. PPFD Targets by Growth Stage
PPFD = Photosynthetic Photon Flux Density (μmol/m²/s).
These are canopy-level averages measured at the top of the tallest cola. A PAR meter (e.g., Apogee MQ-500, Li-190R) or quantum sensor is essential for setup.
Eclipse 328 at 2,600 μmol/s PPF can cover a 4×4 ft (1.2×1.2 m) area at very high intensity. For larger spaces, multiple fixtures are required to achieve uniform PPFD.
| Growth Stage | PPFD Target (μmol/m²/s) | Max PPFD (with CO₂) | Notes |
|---|
| Seedling / Clone | 100–200 | — | Light intensity is critical; too high stunts or burns. Keep lights dimmed or raised. |
| Early Veg (week 1–3) | 200–400 | — | Gradually ramp from 200 to 400 over 2 weeks. |
| Late Veg (week 4+) | 400–600 | 600–700 | Prepare plants for higher flower intensity. |
| Early Flower (week 1–3) | 600–850 | 850–1,000 | Transition slowly over the first week of 12/12. |
| Mid Flower (week 4–6) | 700–900 | 900–1,100 | Peak bulking phase; highest light demand. |
| Late Flower (week 7–9/10) | 600–800 | 800–1,000 | Reduce slightly to avoid stress/bleaching in final ripening. |
| Flush / Last 7–10 days | 400–600 | — | Reduce intensity further; plants are no longer uptaking nutrients at full rate. |
PPFD Uniformity Requirements
- Target variance: ≤ ±10% across the canopy for commercial quality
- Hot spots (>1,200 μmol/m²/s) without supplemental CO₂ will cause photobleaching, tacoing, and heat stress
- Edge drop-off should not exceed 20% from center to corner
Translating to Eclipse 328 Settings
| Scenario | Coverage | PPFD at Canopy | Dimmers Setting (approximate) |
|---|
| 1× fixture, 4×4 ft, 18″ height | 16 sq ft | ~650–750 μmol/m²/s (veg) | ~60–70% power |
| 1× fixture, 4×4 ft, 18″ height | 16 sq ft | ~900–1,000 μmol/m²/s (flower, w/ CO₂) | ~90–100% power |
| 1× fixture, 3×3 ft, 14″ height | 9 sq ft | ~1,100–1,200 μmol/m²/s | 100% power, must supplement CO₂ |
| 1× fixture, 5×5 ft, 24″ height | 25 sq ft | ~500–600 μmol/m²/s | 100% (good for veg or no-CO₂ flower) |
⚠️ Always measure with a PAR meter. These are estimates; actual PPFD depends on reflector design, wall reflectivity (use 95% reflective white/mylar), and hanging height.
3. DLI (Daily Light Integral) Targets by Growth Stage
DLI = total photosynthetic photons delivered per day (mol/m²/day). Formula:
DLI = (PPFD × light-hours × 3,600) / 1,000,000
| Growth Stage | DLI Target (mol/m²/day) | Photoperiod | Equivalent PPFD |
|---|
| Seedling / Clone | 6–10 | 18/6 | 93–154 μmol/m²/s |
| Early Veg | 15–25 | 18/6 | 231–386 μmol/m²/s |
| Late Veg | 25–35 | 18/6 | 386–540 μmol/m²/s |
| Early Flower | 30–38 | 12/12 | 694–880 μmol/m²/s |
| Mid Flower (with CO₂) | 35–45 | 12/12 | 810–1,042 μmol/m²/s |
| Mid Flower (ambient CO₂) | 30–38 | 12/12 | 694–880 μmol/m²/s |
| Late Flower | 25–35 | 12/12 | 579–810 μmol/m²/s |
| Flush | 15–25 | 12/12 | 347–579 μmol/m²/s |
Critical DLI Rule
DLI is what drives yield, not PPFD alone. A low PPFD over a longer photoperiod (e.g., 18/6) can deliver the same DLI as a high PPFD over a shorter photoperiod (12/12). However, cannabis has an upper saturation point — once DLI exceeds ~45 mol/m²/day (without CO₂) or ~65 mol/m²/day (with CO₂ at 1,200–1,500 ppm), yield gains plateau and stress increases.
Eclipse 328 DLI Achievability
At 2,600 μmol/s PPF over a 4×4 ft (1.2×1.2 m) area, the Eclipse 328 delivers roughly 650 μmol/m²/s average at 18″ height. Running 12/12 this gives:
650 μmol/m²/s × 12 hr × 3,600 / 1,000,000 = ~28 mol/m²/day
To reach 38–45 mol/m²/day in mid flower requires:
- Higher intensity (move fixture closer or increase dimmer)
- Or use a reflector hood / scrog to concentrate light
- Or use supplemental side lighting bars
- Or CO₂ enrichment to handle the higher DLI
4. Photoperiod (Light Schedules)
Cannabis is a photoperiod-sensitive short-day plant. The uninterrupted dark period is what triggers and maintains flowering.
Recommended Schedules
| Stage | Schedule | Total Light/Day | Notes |
|---|
| Seedling | 18/6 (or 24/0) | 18–24 hr | 24/0 is controversial; 18/6 allows plants to rest and reduces energy cost. Either works. |
| Vegetative | 18/6 | 18 hr | Standard and proven. Some use 20/4 or 24/0 for faster growth, but 18/6 is optimal for root development vs. stretch. |
| Transition | 18/6 → 12/12 | — | Flip overnight. Sudden change is fine. Some growers do 13/11 or 14/10 for first week to ease the transition, but 12/12 from day 1 is standard. |
| Flowering | 12/12 | 12 hr | Non-negotiable for photoperiod strains. Any light leak during dark period can cause re-veg, hermaphroditism, or bud rot. |
| Final 2 weeks | 12/12 (or 11/13) | 11–12 hr | A few growers reduce to 11/13 in the last week to mimic autumn; may speed ripening. Benefits are marginal. |
| Autoflowering strains | 18/6 (or 20/4) | 18–20 hr | Autoflowers flower based on age, not photoperiod. 18/6 is common; 20/4 can increase yield slightly but may reduce quality. |
Light Schedule Best Practices
- Light leaks: Zero tolerance. Pitch-black during dark period. Use light-proof zippers, ducting baffles, and seal any LEDs on equipment.
- Dawn/dusk simulation: If the Eclipse 328 supports it (smart WiFi), program a 15-minute ramp-up and ramp-down. This mimics natural sunrise/sunset, reduces plant shock, and can improve morning CO₂ uptake.
- Consistency: The circadian clock in cannabis is precise. Lights should turn on and off at exactly the same time every day (±1 min) — no manual toggling.
24-Hour Light Cycle Considerations
| Schedule | Pros | Cons |
|---|
| 24/0 (constant light) | Max growth rate for seedlings | Higher energy cost, no rest period, may increase stress long-term |
| 18/6 | Best balance for veg — growth + rest + efficiency | Slightly slower than 24/0, but healthier |
| 12/12 | Required for photoperiod flowering | Very specific; reduces DLI ceiling (half the time) |
5. VPD (Vapor Pressure Deficit) — Temperature & Humidity
What is VPD?
VPD measures the drying power of the air — the difference between how much moisture the air can hold (at a given temperature) and how much it actually holds. It directly controls transpiration rate, which drives nutrient uptake.
VPD (kPa) = (SVP leaf − SVP air) × relative humidity factor
For cannabis, the optimal VPD range depends on growth stage:
| Growth Stage | Optimal VPD (kPa) | Equivalent RH @ 75°F (24°C) | Equivalent RH @ 80°F (27°C) | Equivalent RH @ 85°F (29°C) |
|---|
| Seedling / Clone | 0.4–0.8 | 70–80% | 70–80% | 75–85% |
| Early Veg | 0.6–1.0 | 65–75% | 62–72% | 60–70% |
| Late Veg | 0.8–1.2 | 55–65% | 50–62% | 48–60% |
| Early Flower | 1.0–1.4 | 48–58% | 45–55% | 42–52% |
| Mid Flower | 1.2–1.6 | 40–50% | 38–48% | 35–45% |
| Late Flower (bulking) | 1.3–1.6 | 38–48% | 35–45% | 32–42% |
| Final 2 weeks (flush) | 1.4–1.8 | 30–40% | 28–38% | 25–35% |
Temperature Targets
| Stage | Day Temp (°F / °C) | Night Temp (°F / °C) | Notes |
|---|
| Seedling | 75–80°F (24–27°C) | 68–72°F (20–22°C) | Warmer for root development; high humidity |
| Veg | 75–82°F (24–28°C) | 65–72°F (18–22°C) | Steady growth; avoid large temp swings |
| Early Flower | 75–80°F (24–27°C) | 64–70°F (18–21°C) | Night drop encourages anthocyanin expression |
| Mid Flower | 78–85°F (26–29°C) w/ CO₂ | 65–72°F (18–22°C) | Higher temp ok with elevated CO₂ |
| Late Flower | 72–78°F (22–26°C) | 60–65°F (16–18°C) | Cooler temps preserve terpenes, reduce mold risk |
| Flush | 70–76°F (21–24°C) | 58–65°F (14–18°C) | Cool finish enhances color and resin quality |
Temperature & Humidity Charts
Seedling / Clone (Target VPD: 0.4–0.8 kPa)
| Temperature | Target RH |
|---|
| 72°F (22°C) | 75–85% |
| 75°F (24°C) | 73–83% |
| 78°F (26°C) | 70–80% |
| 80°F (27°C) | 68–78% |
Vegetative (Target VPD: 0.8–1.2 kPa)
| Temperature | Target RH |
|---|
| 72°F (22°C) | 60–70% |
| 75°F (24°C) | 55–65% |
| 78°F (26°C) | 52–62% |
| 80°F (27°C) | 50–60% |
| 82°F (28°C) | 48–58% |
Flowering (Target VPD: 1.2–1.6 kPa)
| Temperature | Target RH |
|---|
| 72°F (22°C) | 45–55% |
| 75°F (24°C) | 40–50% |
| 78°F (26°C) | 38–48% |
| 80°F (27°C) | 35–45% |
| 82°F (28°C) | 33–43% |
VPD Management with the Eclipse 328
- The Eclipse 328's high efficiency (3.28 μmol/J) means less heat per photon compared to HPS or older LED fixtures. This is a significant advantage for VPD management — you can deliver high PPFD without overheating the canopy.
- However, LED fixtures (especially high-output bar-style) produce less radiant heat than HPS. This means leaf temperature is closer to ambient air temperature, which increases the leaf-to-air VPD gradient. Growers switching from HPS to LED often need to run 2–5°F warmer to maintain the same VPD.
- Use an infrared thermometer to measure leaf surface temperature (typically 1–4°F below ambient). For LED grows, keep ambient temp slightly higher to compensate.
VPD Quick Reference — Corrective Actions
| Problem | Symptom | VPD Issue | Fix |
|---|
| Slow growth, wilting | Leaves drooping, edges curling up | VPD too high (air too dry) | Raise RH (humidifier), lower temp |
| Slow growth, mold risk | Leaves drooping, stem weak, PM spots | VPD too low (air too wet) | Lower RH (dehumidifier), raise temp, increase airflow |
| Leaf tacoing | Leaf edges curling upward, crispy | PPFD too high AND/OR VPD too high | Reduce light intensity + raise RH |
| Guttation | Water droplets on leaf edges | VPD too low + high transpiration | Lower RH slightly, increase airflow |
6. CO₂ Enrichment
Why CO₂ Matters
Cannabis is a C3 plant. At elevated CO₂ (1,200–1,500 ppm), the plant can:
- Tolerate higher PPFD (up to 1,100 μmol/m²/s) without stress
- Increase photosynthetic rate by 30–50%
- Shorten flower time by 7–14 days in some cases
- Improve bud density and weight
CO₂ Guidelines
| Condition | CO₂ Level (ppm) | When to Use |
|---|
| Ambient (no supplement) | 400–450 | Standard grows, PPFD ≤ 600 μmol/m²/s |
| Low supplement | 800–1,000 | PPFD 600–900 μmol/m²/s, better yield |
| High supplement (commercial) | 1,200–1,500 | PPFD 900–1,100 μmol/m²/s, sealed room required |
| Maximum | 1,500 | Diminishing returns above 1,500 ppm; becomes toxic above 2,000 ppm |
CO₂ Schedule
- When: Lights ON only (CO₂ uptake depends on photosynthesis)
- Turn off CO₂ 15–30 min before lights OFF — plants slow CO₂ uptake and it wastes gas
- Stage-specific: Only use CO₂ from mid-veg through mid-flower. Stop CO₂ in the last 2–3 weeks of flower (plants no longer efficiently use it and it can promote mold in dense buds)
- Sealed room required for high CO₂ — exhaust fans purge CO₂. In non-sealed rooms, CO₂ supplementation is largely wasted
Eclipse 328 + CO₂ Synergy
The Eclipse 328 at 2,600 μmol/s PPF is ideal for CO₂-enriched environments. Without CO₂, the fixture may need to be dimmed to ~60–70% to avoid hitting >900 μmol/m²/s. With CO₂ at 1,200 ppm, the fixture can be run at 90–100%, maximizing the value of every diode.
7. Mounting Height & Light Distribution
General Height Guidelines
| Stage | Distance from Canopy | PPFD Effect |
|---|
| Seedlings / Clones | 30–36 in (76–91 cm) | Achieves 100–200 μmol/m²/s |
| Vegetative | 18–24 in (46–61 cm) | Achieves 400–600 μmol/m²/s |
| Early Flower | 14–18 in (36–46 cm) | Achieves 700–900 μmol/m²/s |
| Mid/Late Flower | 12–16 in (30–41 cm) | Achieves 900–1,100 μmol/m²/s (with CO₂) |
These are starting points. Always verify with a PAR meter — every grow room has different reflectivity.
Inverse Square Law Reminder
PPFD decreases with the square of distance from the light source.
Doubling the height → ¼ the PPFD. Small height adjustments make a large difference.
Eclipse 328 Coverage
- Optimal coverage area: 4×4 ft (1.2×1.2 m) at 18″ height for flower
- Maximum coverage: 5×5 ft (1.5×1.5 m) at 24″ height for veg or lower-light flower
- Intensive coverage: 3×3 ft (0.9×0.9 m) at 12–14″ height for high-DLI flower with CO₂
Tips for Even PPFD Distribution
- Use 95%+ reflective walls (white paint, Mylar, Orca Film) — this recovers light that would otherwise be lost, improving edge PPFD by 20–30%
- Scrog (Screen of Green) — creates a flat, even canopy so all colas receive uniform PPFD
- Rotate pots weekly — mitigates any hot/cold spots in the room
- Use a PAR map — measure PPFD at 9+ grid points across the canopy and adjust fixture height/angle
8. K99 Eclipse 328 — Specific Recommendations
Fixture Specifications Recap
| Parameter | Value |
|---|
| Model | Eclipse 328 |
| PPF | 2,600 μmol/s |
| Efficiency | 3.28 μmol/J |
| LED Type | Samsung LM301H EVO (white) + OSRAM deep red (660 nm) |
| Control | WiFi + BLE 5.2 smart app |
| Coverage | 4×4 ft flower / 5×5 ft veg |
| Power Draw | ~793 W (at 100%) |
Spectrum Configuration
Vegetative Profile (18/6 schedule):
| Channel | Power % | Purpose |
|---|
| White LM301H EVO (cool ~5000K bin) | 80–100% | Broad spectrum, blue-rich for compact growth |
| OSRAM Deep Red (660 nm) | 20–30% | Supplement deep red for chlorophyll a; boost photosynthesis without stretch |
| Resulting PPFD | 400–600 μmol/m²/s | At 18–24″ height |
Flowering Profile (12/12 schedule):
| Channel | Power % | Purpose |
|---|
| White LM301H EVO (warm ~3000K bin) | 60–80% | Broad-spectrum base, warmer for flower |
| OSRAM Deep Red (660 nm) | 60–80% | Primary flower driver — deep red drives bud density |
| Resulting PPFD | 800–1,000 μmol/m²/s | At 12–16″ height, with CO₂ |
Note: If the Eclipse 328 has independent dimming channels for white vs. deep red via the WiFi app, use the above ratios. If it uses a single-channel dimmer, adjust height/power to achieve target PPFD.
Smart WiFi Control — Pro Tips
- Sunrise/Sunset dimming: Program a 15-minute ramp at lights-on and lights-off. This reduces stress and allows plants to gradually adjust stomatal opening.
- Weather simulation: If the app supports it, program a 5–10% intensity dip in the middle of the day (simulating cloud cover). Some growers report this triggers a mild stress response that can increase terpene production.
- End-of-flower fade: Reduce intensity by 10–15% per week over the last 2–3 weeks to simulate autumn light decline. This signals plants to allocate energy to resin and ripening.
- Dew point avoidance: If the WiFi app includes room sensor integration, set a rule to dim lights by 10–20% if canopy temperature exceeds 88°F (31°C) to prevent heat stress.
Room Setup Diagram
┌─────────────────────────────────────┐
│ K99 Eclipse 328 │
│ (12–18″ above canopy) │
├─────────────────────────────────────┤
│ │
│ ┌───┐ ┌───┐ ┌───┐ ┌───┐ │
│ │ P │ │ P │ │ P │ │ P │ ← 4×4 │
│ └───┘ └───┘ └───┘ └───┘ tray │
│ │
├─────────────────────────────────────┤
│ ← Oscillating fans → │
├─────────────────────────────────────┤
│ ← Intake (bottom) │ Exhaust (top) → │
└─────────────────────────────────────┘
- Airflow: Minimum 1–2 oscillating fans at canopy level. Commercial rooms: 4–8 air exchanges per hour.
- Exhaust: Carbon filter + inline fan sized to room volume (e.g., 6″ for 4×4, 8″+ for 5×5+).
- Dehumidifier: Essential in flower. Should maintain 35–50% RH.
- Supplemental side lighting (optional): For large commercial grows, adding 660 nm strip LEDs on vertical walls can recover lower-bud yield by 15–25%.
9. Quick Reference Cheat Sheet
One-Page Summary
| Parameter | Seedling | Veg | Early Flower | Mid Flower | Late Flower | Flush |
|---|
| PPFD (μmol/m²/s) | 100–200 | 200–600 | 600–850 | 700–1,000 w/ CO₂ | 600–800 | 400–600 |
| DLI (mol/m²/day) | 6–10 | 15–35 | 30–38 | 35–45 w/ CO₂ | 25–35 | 15–25 |
| Photoperiod | 18/6 or 24/0 | 18/6 | 12/12 | 12/12 | 12/12 | 12/12 |
| Temp (°F) | 75–80 | 75–82 | 75–80 | 78–85 (w/ CO₂) | 72–78 | 70–76 |
| Temp (°C) | 24–27 | 24–28 | 24–27 | 26–29 | 22–26 | 21–24 |
| RH (%) | 70–80 | 55–65 | 48–58 | 40–50 | 35–45 | 30–40 |
| VPD (kPa) | 0.4–0.8 | 0.8–1.2 | 1.0–1.4 | 1.2–1.6 | 1.3–1.6 | 1.4–1.8 |
| CO₂ (ppm) | 400–450 | 400–800 | 800–1,200 | 1,200–1,500 | 400–800 | 400–450 |
| Light height | 30–36″ | 18–24″ | 14–18″ | 12–16″ | 12–16″ | 14–18″ |
| Spectrum | Blue-heavy | Blue-heavy | Red-heavy | Red-heavy (deep red on) | Red-heavy | Reduce all |
| R:B Ratio | 1:1 | 1.2–1.5:1 | 4:1 | 5–6:1 | 5:1 | 3:1 |
Daily Checklist for Growers
| Task | Frequency | Tool |
|---|
| Measure PPFD at canopy | Once/week | PAR meter |
| Check temperature & RH | Daily | Thermo-hygrometer + IR gun |
| Calculate VPD | Daily | VPD chart or app (e.g., Pulse, Grower's Ally) |
| Verify photoperiod timer | Weekly | Check timer accuracy |
| Inspect leaf temperature | 2×/week | IR thermometer |
| Monitor CO₂ levels (if used) | Daily | CO₂ monitor / controller |
| Clean LED lenses | Every 2 weeks | Isopropyl alcohol + microfiber |
| Check light uniformity | Monthly | Grid PAR measurement |
Common Troubleshooting
| Issue | Likely Cause | Fix |
|---|
| Leaves "tacoing" upward | PPFD too high + low RH | Raise lights, increase humidity, reduce dimmer |
| Stretching between nodes | Spectrum too red / PPFD too low | Increase blue light power, decrease height |
| Bleached buds (white tips) | PPFD >1,200 at canopy | Raise light or dim, check for hot spots |
| Slow growth / dark green droop | VPD too low (too humid) | Dehumidify, raise temperature, increase air movement |
| Leaf edges crisp, brown | VPD too high (too dry) + high PPFD | Humidify, lower temp, lower PPFD |
| Mold on buds (botrytis) | RH too high in late flower | Dehumidify to ≤45%, improve airflow, defoliate |
| Hermaphrodite / seeds | Light leaks during dark period | Fix all light leaks in the room |
References & Further Reading
- Bugbee, B. (2016). "The Economics of Supplemental Lighting." Acta Horticulturae.
- Chandra, S. et al. (2008). "Photosynthetic response of Cannabis sativa to CO₂ enrichment." Journal of Industrial Hemp.
- Darko, E. et al. (2014). "Photosynthesis under artificial light: the shift in spectral composition." Plant Science.
- Faust, J.E. (2016). "Light management in controlled environments." University of Florida Extension.
- Nemali, K.S. & van Iersel, M.W. (2004). "Light intensity and spectral quality effects on growth and development." HortScience.
- Vanhaecke, L. et al. (2021). "Optimizing LED light spectra for cannabis production." Frontiers in Plant Science.
- Zheng, Y. (2022). "Cannabis Light Quality, Quantity, and Duration." University of Guelph — Controlled Environment Systems Research Facility.
Document prepared for K99 LABS. For verification of Eclipse 328 specifications, always refer to the official K99 LABS product datasheet. Growing parameters are general guidelines — cultivar-specific tuning is recommended.