Aquarium Lighting Guide: LED Options, PAR, and Plant Requirements

Lighting is one of the most misunderstood aspects of aquarium keeping. The right light brings out fish colors, supports plant growth, and creates the ambiance you want. The wrong light causes algae outbreaks, stunts plants, or wastes electricity.

This guide demystifies aquarium lighting, from basic LED fixtures to advanced concepts like PAR and spectrum requirements.

Why Aquarium Lighting Matters

For Fish:

Displays natural colors vividly
Regulates circadian rhythm (day/night cycle)
Affects behavior and breeding
Reduces stress with consistent schedule

For Plants:

Drives photosynthesis (energy production)
Determines growth rate and health
Affects leaf coloration
Required for any plant growth at all

For Algae Control:

Excess light causes algae explosions
Insufficient light favors certain algae types
Balance is key: match light to plant mass and nutrients

For Viewing:

Makes your aquarium the focal point it should be
Creates atmosphere (warm, cool, natural)
Allows enjoyment during evening hours

Types of Aquarium Lights

LED Lights (Recommended)

Why LEDs Dominate:

Energy efficient (save 70%+ vs old technology)
Long lifespan (30,000-50,000 hours)
Low heat output (safer for fish)
Full spectrum options available
Adjustable intensity and color
Slim, modern designs

Types of LED Fixtures:

1. Basic LED Hoods:

Integrated with tank hood
Often included with starter kits
Low intensity
Best for: Fish-only tanks, very low-tech setups

2. Clip-On LED Lights:

Attach to tank rim
Adjustable gooseneck
Various intensities available
Best for: Nano tanks, betta tanks, small planted tanks
Popular: Nicrew Clip-On, Hygger Clip-On

3. LED Light Bars/Strips:

Sit on tank rim or hang above
Length matches tank dimensions
Various intensities and features
Best for: Standard rectangular tanks
Popular: NICREW Classic, Aqueon LED

4. High-Performance LED Fixtures:

Programmable, multi-channel
High PAR output
Full spectrum with RGB
Built-in timers and dimmers
Best for: Planted tanks, high-tech setups
Popular: Chihiros WRGB, Twinstar, ONF, ADA Solar

5. Hanging/Pendant LED:

Suspended above tank
Excellent for open-top setups
High-end aesthetics
Best for: Show tanks, aquascaping competitions
Popular: Kessil, Chihiros pendant

Fluorescent Lights (Legacy Technology)

T5 and T8 Fixtures:

Older technology still available
Require bulb replacement every 1-2 years
Higher heat output
Lower efficiency than LEDs
Best for: Replacing existing fluorescent setups

Verdict: Only choose if replacing like-for-like. LEDs are superior in every way.

Understanding Light Measurements

PAR (Photosynthetically Active Radiation)

What Is PAR:

Measures usable light for photosynthesis
Range: 400-700 nanometers (visible light)
Measured in micromoles per second per meter² (μmol/m²/s)
Most accurate measure for plant growth

PAR Categories:

Low Light (15-30 PAR at substrate):

Anubias, Java Fern, Java Moss, Cryptocoryne
Slow growth, minimal algae risk
Suitable for low-tech tanks

Medium Light (30-50 PAR at substrate):

Most stem plants, Vallisneria, Amazon Sword
Moderate growth rates
Requires balanced nutrients

High Light (50+ PAR at substrate):

Carpeting plants, red plants, demanding species
Fast growth, requires CO2
Higher algae risk if unbalanced

How to Measure PAR:

PAR meter (expensive but accurate): $200-400
Phone apps (approximate): $5-20
Reference charts from manufacturers
Community measurements for popular lights

Lumens and Lux

Lumens:

Total light output from fixture
Not useful for aquariums (doesn’t account for spectrum or spread)
Marketing specification mostly

Lux:

Light intensity at a specific distance
One lumen per square meter
Better than lumens but still not as useful as PAR

Rule: Focus on PAR for planted tanks. Ignore lumen ratings.

Kelvin (Color Temperature)

What Is Kelvin:

Measures light color “warmth”
Lower K = warmer/yellower (2700K)
Higher K = cooler/bluer (10000K+)

Common Aquarium Kelvin Ratings:

6500K (Daylight):

Natural white light
Best for plant growth
Accurate color rendering
Recommended for most tanks

8000K-10000K:

Cooler, bluer white
Common in marine tanks
Can make some fish colors pop
Still adequate for plants

RGB/WRGB:

Multi-color LEDs
Adjustable color spectrum
Red enhances red plants/fish
Blue enhances blue fish/shrimp
Green for plant health

Full Spectrum:

Covers entire visible range
Mimics natural sunlight
Best plant growth
Most natural appearance

Choosing Light by Tank Type

Fish-Only Tanks

Requirements:

Viewing enjoyment
Fish circadian rhythm
Minimal algae control

Recommended Lights:

Basic LED hood or strip
8-10 hours daily
Any spectrum (fish colors dictate preference)
6500K for natural look
Lower intensity fine

Examples:

Aqueon LED Hood
NICREW Classic LED
Any basic aquarium LED

Low-Tech Planted Tanks

Requirements:

Support easy plants
Minimal algae trigger
No CO2 supplementation

Recommended Lights:

Low to medium PAR (15-30 at substrate)
6-8 hours daily
6500K or full spectrum
Timer essential

Examples:

NICREW Classic LED (dimmed or raised)
Finnex Stingray
Low-powered clip-on LEDs

High-Tech Planted Tanks

Requirements:

High PAR for demanding plants
Even spread across tank
Adjustable intensity
Full spectrum with RGB

Recommended Lights:

High PAR (50+ at substrate)
8-10 hours daily
Programmable for dawn/dusk effect
CO2 required at this light level
Timer and dimmer built-in

Examples:

Chihiros WRGB II
Twinstar S-Series
ONF Flat Nano
ADA Solar RGB

Specialized Lighting Needs

Red Plants (Ludwigia, Rotala):

Strong red spectrum
High intensity
Iron supplementation
WRGB lights excel here

Carpeting Plants:

High intensity at substrate
Even coverage
Consider multiple fixtures for large tanks
CO2 required

Tall Tanks (18+ inches):

High-output fixtures
Pendant or hanging lights
PAR drops significantly with depth
Research penetration depth

Lighting Duration (Photoperiod)

Standard Recommendations:

Fish-Only: 8-10 hours

Low-Tech Planted: 6-8 hours

High-Tech Planted: 8-10 hours

Algae-Prone Tanks: Start with 6 hours, increase gradually

Photoperiod Breakdown:

Simple Schedule:

Lights on: 10 AM
Lights off: 6 PM
Total: 8 hours

Advanced Schedule (with dimmable lights):

Dawn (10%): 9-10 AM
Full intensity: 10 AM-5 PM
Dusk (10%): 5-6 PM
Off: 6 PM

The Break Method:

On: 8 AM-12 PM (4 hours)
Off: 12 PM-4 PM (4 hours break)
On: 4 PM-8 PM (4 hours)
Total: 8 hours

The break interrupts algae’s photosynthesis more than plants’, helping control outbreaks.

Lighting Calculations by Tank Size

General LED Wattage Guidelines:

Low-Tech (No CO2):

1-2 watts per gallon (modern LED equivalent)

Medium-Tech:

2-3 watts per gallon

High-Tech (With CO2):

3-5 watts per gallon

Important Note: Modern LEDs are more efficient than old wattage guidelines. A 20-watt LED can outperform a 40-watt fluorescent. Focus on PAR if possible.

Tank-by-Tank Recommendations:

10 Gallon:

Clip-on LED: 8-12 watts
Examples: Finnex Stingray, Hygger Clip-On

20 Gallon:

Light bar: 12-18 watts
Examples: NICREW Classic (adjustable)

40 Gallon:

Dual light bars or single high-output
24-36 watts
Examples: Two NICREW lights, Chihiros A-Series

55 Gallon:

36-48 inch fixture
30-50 watts
Examples: Fluval 3.0, Twinstar 600

75+ Gallon:

Multiple fixtures or high-output pendant
50-100+ watts total
Examples: Multiple Chihiros, Kessil pendant

Popular Aquarium Light Reviews

Budget Picks (Under $50)

NICREW Classic LED:

Price: $25-40 depending on size
PAR: Low to medium
Best for: Low-tech planted, fish-only
Pros: Affordable, reliable, decent spread
Cons: No timer, fixed spectrum

Hygger Clip-On:

Price: $20-30
PAR: Low
Best for: Nano tanks, betta tanks
Pros: Gooseneck adjustable, compact
Cons: Limited coverage

Mid-Range ($50-150)

Finnex Stingray:

Price: $50-80
PAR: Low to medium
Best for: Low-tech planted
Pros: Slim design, good color rendition
Cons: Fixed intensity

NICREW Planted LED:

Price: $60-100
PAR: Medium
Best for: Medium-tech planted
Pros: Timer included, adjustable legs
Cons: Moderate PAR only

Fluval Plant 3.0:

Price: $100-200
PAR: Medium to high
Best for: Medium to high-tech
Pros: App control, programmable, excellent spectrum
Cons: App can be finicky

Premium ($150+)

Chihiros WRGB II:

Price: $150-300
PAR: High
Best for: High-tech aquascapes
Pros: Exceptional PAR, RGB channels, app control
Cons: Expensive, requires separate controller for features

ONF Flat Nano:

Price: $150-250
PAR: Medium to high
Best for: Show tanks, aquascaping
Pros: Beautiful design, excellent color, dimmable
Cons: Limited to smaller tanks

Twinstar S-Series:

Price: $200-400
PAR: Very high
Best for: Professional aquascapes
Pros: Exceptional build quality, light output
Cons: Expensive, overkill for most

DIY and Alternative Lighting

Shop Lights (Budget Option):

6500K LED shop lights from hardware stores
$20-40 for large fixtures
Mount above tank with chains or stand
Great for multiple tanks or fish-only

CFL Bulbs in Clamp Lamps:

6500K compact fluorescent bulbs
Very inexpensive setup
Good for nano tanks
Inefficient compared to LEDs

Build Your Own LED:

LED strips + power supply + frame
Customizable spectrum and intensity
Cost-effective for multiple tanks
Requires electrical knowledge

Installation Tips

Height Above Tank:

Lower = Higher PAR but smaller spread
Higher = Lower PAR but larger spread
Adjustable hanging kits ideal
Start higher and lower gradually

Coverage:

Light should cover entire tank footprint
Overlap multiple fixtures if needed
PAR should be relatively even across tank

Glare and Reflections:

Position to avoid glare for viewing
Consider tank placement relative to windows
Black backgrounds reduce light spill

Timers Are Essential:

Consistency prevents algae
Fish need regular day/night cycle
Digital timers: $10-20
Smart plugs with scheduling: $15-30

Troubleshooting Lighting Problems

Algae Explosion:

Cause: Too much light, too long duration, or imbalance with nutrients
Solution: Reduce duration by 2 hours, raise light fixture, add more plants

Plants Not Growing:

Cause: Insufficient PAR, wrong spectrum, or insufficient duration
Solution: Test PAR at substrate, ensure 6500K+, increase to 8 hours

Leggy, Tall Plants (Etiolation):

Cause: Insufficient light, plants reaching for more
Solution: Increase intensity or lower fixture

Red Plants Turning Green:

Cause: Insufficient red spectrum or intensity
Solution: Add RGB light or increase intensity, supplement iron

Fish Hiding:

Cause: Light too bright, no shaded areas
Solution: Add floating plants, dim light, create caves

Advanced Lighting Concepts

Color Channels (RGB Lights):

Red: Enhances red plants and fish, promotes flowering
Green: Balances spectrum for plant health
Blue: Enhances blue fish, moonlight effect, promotes compact growth
White: Overall brightness and natural appearance

Dimming and Ramping:

Mimics natural sunrise/sunset
Reduces shock to fish
Can extend photoperiod with lower intensity
Most high-end lights include this feature

Light Spread and Optics:

Lenses focus light (higher PAR, smaller spread)
Diffusers spread light (lower PAR, larger spread)
Consider tank dimensions when choosing

Cost Considerations

Initial Investment:

Budget LED: $25-50
Mid-range: $75-150
Premium: $200-400

Operating Costs (Annual):

LED: $5-20 (very efficient)
Fluorescent: $20-40
Metal halide: $50-100 (rarely used now)

Lifespan:

Quality LEDs: 5-10 years
Budget LEDs: 3-5 years
Fluorescent bulbs: 1-2 years

Conclusion

Choose your light based on your goals. Fish-only tanks need minimal lighting—any basic LED works. Planted tanks require more thought: match PAR to your plant selection and CO2 usage.

Start conservative with duration (6 hours) and intensity, then adjust based on plant growth and algae. A timer is non-negotiable—consistency matters more than intensity.

Remember: You can always add more light, but you can’t undo an algae outbreak. Start low, go slow, and enjoy watching your underwater garden flourish.

Ready to choose plants for your lighting setup? Read our beginner plant guide to match plants to your light level.