LED lighting for a planted discus aquarium: 5 models + setup
LED lighting for a planted discus aquarium — Kelvin 5500-7000K, PAR 30-50, 5 top models (Chihiros WRGB, Fluval Plant 3.0, Twinstar, Aquael, ONF), a setup by volume and how to read algae.
Quick summary
- Discus compromise: moderate light — enough for plants (PAR 30-50), not intense
- Kelvin: 5500-7000 K for planted / 3000-5000 K for a Rio Negro biotope
- Hours/day: 8h standard on a timer, max 10h; gradual sunrise/sunset is ideal
- 5 top models: Chihiros A/WRGB II, Fluval Plant 3.0, Twinstar, Aquael Leddy, ONF Flat One
- Pro tip: floating plants (Amazon frogbit) over 30-50% of the surface = natural shade
- Algae are a signal — reduce the light, don't increase fertilizer
In short
- Discus compromise: moderate light — enough for plants (PAR 30-50), not intense (which stresses discus and feeds algae).
- Kelvin: 5500-7000 K for planted / 3000-5000 K for a Rio Negro biotope.
- Hours/day: 8h standard on a timer, max 10h. Gradual sunrise/sunset is ideal for discus.
- 5 top EU models: Chihiros A/WRGB II (best value), Fluval Plant 3.0 (Bluetooth), Twinstar E-Line/III (premium plants), Aquael Leddy Slim (budget), ONF Flat One (aesthetic).
- Pro tip: floating plants (Amazon frogbit) over 30-50% of the surface → natural shade, calmer discus.
What you'll learn
Lighting a planted discus aquarium (Symphysodon) is a compromise between the plants' needs (intensity for photosynthesis) and the discus's comfort (they prefer moderate diffuse light, not intense direct light). This guide shows you the technical parameters (Kelvin, PAR, W/L), 5 top LED models, a setup by volume, techniques (siesta, sunrise/sunset) and algae as a signal.
Essential technical parameters
1. Kelvin (color temperature)
| Kelvin | Color | Suitable for discus? |
|---|---|---|
| 2700-3500 K | Warm yellow | ⭐⭐ Blackwater biotope |
| 5500-6500 K | Neutral "daylight" | ⭐⭐⭐⭐⭐ Recommended for planted |
| 6500-7000 K | White with a cool tint | ⭐⭐⭐⭐ High-demand plants |
| 7000-10000 K | Cool bluish | ⭐⭐ Stresses discus |
2. PAR (Photosynthetically Active Radiation)
| PAR | Level | Suitable plants |
|---|---|---|
| <30 | Low | Anubias, Java fern, Bucephalandra |
| 30-50 | Medium (ideal for discus) | Echinodorus, Cryptocoryne, Vallisneria |
| 50-100 | High | Carpet plants — NEED CO2, stressful for discus |
| >100 | Very high | Incompatible with discus |
3. Watts per liter (W/L)
| Tank type | W/L (LED) |
|---|---|
| Biotope / minimal plants | 0.2-0.3 W/L |
| Moderately planted (recommended) | 0.3-0.5 W/L |
| Densely planted with CO2 | 0.5-1.0 W/L |
Example: a 250L (66 US gal) moderately planted tank → 75-125W of LED total.
Lighting hours per day
| Duration | Result |
|---|---|
| 6h | Minimum — biotope and low-light plants |
| 8h | Optimal for planted + discus |
| 10h | Maximum — algae risk if you fertilize heavily |
| 12h+ | ❌ Heavy algae + stressed discus |
Use a programmable timer (cheap) or a lamp with sunrise/sunset (Chihiros, Fluval, Twinstar) — a 30-60 min transition. An abrupt on/off startles discus.
The "siesta" technique (midday break)
- 3h of light in the morning (8-11)
- 2h break (11-13) — no light, CO2 builds up naturally
- 5h of light in the afternoon (13-18)
Noticeably reduces BBA and GSA algae. Fine for discus — they're used to natural shade.
5 top LED models for discus
1. Chihiros A / WRGB / Vivid ⭐⭐⭐⭐⭐
Bluetooth app, adjustable Kelvin 5000-7500 K, gradual sunrise/sunset, a 5+ year lifespan. Tiers: A-Series (entry), WRGB II (mid), Vivid II (premium). Widely available across EU aquascaping retailers.
2. Fluval Plant 3.0 ⭐⭐⭐⭐
Bluetooth + app, full spectrum (5 LED colors), pre-set programs. Sizes for 61-85 cm (24-34 in), 91-122 cm (36-48 in) and 122-153 cm (48-60 in) tanks.
3. Twinstar E-Line / III ⭐⭐⭐⭐⭐
A spectrum optimized for photosynthesis, high PAR, visibly more colorful plants. Downside: no Bluetooth on the E-Line. Tiers: E-Line (mid) and III Series (premium).
4. Aquael Leddy Slim Sunny / Plant ⭐⭐⭐
The most accessible, widely available. Tiers: Leddy Slim Sunny, Leddy Slim Plant, Leddy Pro Plant. Good for 60-150L (16-40 US gal).
5. ONF Flat One Series ⭐⭐⭐⭐⭐
Premium, minimalist aesthetics. Tiers: Flat Nano and Flat One Plus.
Setup by tank volume
100-150L (26-40 US gal)
- 1 × Chihiros A-Series 60 OR Aquael Leddy Plant 80
- 8h/day, 60-80% intensity
200-250L (53-66 US gal)
- 1 × Chihiros A-Series 80 OR Fluval Plant 3.0 32W
- 8h/day, 60-70% intensity + Amazon frogbit for diffusion
300L / 79 US gal (recommended for discus)
- 1 × Chihiros WRGB II 90 OR Twinstar E-Line 90
- 8h/day with 30-min sunrise/sunset, 60-70% intensity
400L+ (105+ US gal)
- 2 × Chihiros A-Series 80
- OR 1 × Fluval Plant 3.0 59W
- OR 1 × Twinstar III 120
Algae as a signal
| Algae type | Lighting cause | Action |
|---|---|---|
| Brown on glass (diatoms) | New tank <3 months — NORMAL | Wait |
| Green spots on leaves (GSA) | Strong light + lack of PO4 | Reduce 1-2h |
| Green strands (hair algae) | 10+ hours/day | Cut to 8h, run a siesta |
| Black tufts on wood (BBA) | Direct flow + constant light | Add a 2h siesta |
| Green water | Direct sun or LED too intense | Move the tank, reduce intensity |
The rule: algae → REDUCE the light (do NOT increase fertilizer).
Floating plants — a secret for discus
Amazon frogbit, Pistia stratiotes float at the surface and:
- ✅ Filter the light — diffuse shade
- ✅ Absorb NO3 and NH3 — competing with algae
- ✅ Create refuge zones
- ✅ Act as a health indicator
Ideal coverage: 30-50% of the surface. Inexpensive — a small bunch covers a tank.
Did you know?
Wild discus live in shaded, tannin-stained Amazon waters where little direct light reaches the bottom — which is exactly why intense, "high-tech" planted lighting often makes them look washed out and skittish rather than vibrant. Their cells contain pigment cells (chromatophores) that respond to their surroundings: against a dark background and diffuse light, many discus actually display richer, deeper colors than under a bright, cool-white fixture. That's the real reason floating-plant shade and warmer color temperatures are recommended here — it's about the fish, not just the plants.
Common mistakes
❌ LED directly above open water without a lid — splashes ruin the LED.
❌ 12 hours/day to grow plants faster — backwards; heavy algae instead.
❌ A cheap underpowered LED for an 80 cm (32 in) tank — low PAR, incomplete spectrum.
❌ Cool 7500K+ light — pale discus.
❌ Running it at 100% max — excess = just algae.
❌ Abrupt on/off — startled discus. Use sunrise/sunset.
❌ Tank next to a window — direct sun = an algae explosion.
❌ No lid — discus jump.
Total budget (250L / 66 US gal) — Romania estimate
Costs vary widely by country and supplier — the figures below are a Romania estimate (2026), for orientation only.
| Element | Cost (RON, Romania estimate) |
|---|---|
| Entry LED (Chihiros A / Aquael Leddy) | 300-550 RON |
| Premium LED (Fluval / Twinstar / WRGB II) | 700-1,200 RON |
| Digital timer | 30-60 RON |
| Floating plants | 30-60 RON |
| Entry total | 360-670 RON |
| Premium total | 760-1,320 RON |
Final checklist
- ☐ Kelvin: 5500-7000 K planted / 3000-5000 K biotope
- ☐ Intensity: 0.3-0.5 W/L moderately planted
- ☐ 8h/day on a programmable timer
- ☐ Gradual sunrise/sunset — avoid abrupt on/off
- ☐ Floating plants over 30-50% of the surface
- ☐ Tank AWAY from a window
- ☐ Lid mandatory
- ☐ Algae → REDUCE the light (do NOT increase fertilizer)
- ☐ Siesta technique if you see BBA
What to do next
🌿 Plants: Discus-compatible plants.
💊 Fertilization: Fertilizing a planted aquarium.
🪵 Hardscape: Driftwood and hardscape.
🛒 Shop: The discus.ro shop — lighting.