Healpful Tips

Aquarium Lighting

Aquarium lighting is often overlooked by most hobbyists; hence, it is important to know that proper lighting plays a vital role in the success of all aquarium inhabitants. Proper aquarium lighting provides vital energy to photosynthetic organisms such as corals, anemones or plants. Aquarium lighting is the primary light source, and in most cases, the only light source, that will influence fish behaviour, physiology and the overall health and well-being of the organisms in the aquarium.

There are a wide variety of lighting options for hobbyists. This diverse selection allows hobbyists of all levels to provide the appropriate lighting conditions for their particular aquarium inhabitants. Aquarium light fixtures are generally grouped into three general categories: Normal output fluorescent lighting, compact fluorescent lighting, and high intensity metal halide lighting. Fluorescent light fixtures are a great choice for fresh and marine fish-only aquariums. There is a wide selection of these energy-efficient light fixtures and you may use different bulbs combination to provide the appropriate lighting for your aquarium inhabitants.

Aquarium lighting fixtures are usually labelled with a Kelvin rating “K”. This rating is a number, usually: 5,500, 6,500, 10,000 or 20,000, followed by the letter K. Kelvin ratings indicate the wavelength or colour spectrum provided by the lighting fixture. Shorter wavelengths, like 5,500 and 6,500, provide a reddish or yellowish cast, and longer wavelengths are blue-violet in colour. Most aquatic plants can thrive under lights with shorter wavelengths, but reddish-toned plants and coral reefs require the ultraviolet rays found in 10,000 to 20,000 K fixtures. Additionally, tall tanks may need higher-Kelvin lighting because longer wavelengths are able to penetrate deeper water.

Normal Output Fluorescent Lighting:

50/50 or Actinic White Bulbs - Emit a blend of white and blue light that helps recreate marine light conditions. Generally, it is a combination of 10,000°K white light and blue actinic light. This blended light encourages photosynthetic coral growth while providing light that is pleasing to the human eye.
Colour-Enhancing Bulbs - Emit light from the "warmer" end of the colour spectrum to augment or enrich colour. Designed to display the colours of your fish to their fullest. Ideal for fish-only fresh and saltwater aquariums.
Full Spectrum/Daylight Bulbs - Emit all the wavelengths of visible light and closely approximates the visual effects of natural sunlight. Contains a blend of all the colours of the colour spectrum. These general-purpose bulbs are ideal for all types of fresh and saltwater aquariums.
Actinic Bulbs - Emit light predominantly from the blue end of the colour spectrum. Recreates light conditions found in deep water and provides the light energy necessary for proper photosynthetic coral growth. Actinic bulbs are ideal for reef aquariums.
Plant Bulbs - Emit light that stimulates plant growth. With peak light emissions in both the red and blue regions of the colour spectrum, this light maximizes photosynthetic activity for lush planted aquariums
High-Intensity Bulbs - Emit bright light with a high colour temperature (Kelvin-rating) usually ranging from 10,000°K to 20,000°K. It is a crisp white light commonly used in conjunction with actinic bulbs in marine aquariums. 20,000°K bulbs will emit a brilliant white-blue light that appears "cooler" to simulate deeper marine light conditions.

Lighting Overview

Bulb Type Watts Bulb Life Kelvin Rating Benifits Limitations Typical Use
7 - 25
with colour
of bulb

Inexpensive; multiple colours Narrow spectrum; lower light intensity; high heat Small fish only; beginner's start-up kits
Standard Fluorescent
15 - 40
6 - 18 months
Wide range of colours, sizes; aesthetic; efficient; cool; inexpensive Not ideally suited for
photosynthetic plants or
Fresh or saltwater community aquarium or mini or micro reef with low light corals and
T-5 HO Fluorescent
24 - 54
16 - 24 months
Longevity; high intensity; small size; cool running Not  ideally suited for aquariums more than 24" deep Reef less than 24" deep; freshwater planted
VHO Fluorescent
75 - 165
4 - 18 months
Large selection of sizes; longer bulb life than standard fluorescent

Higher heat, may require a chiller to Control water Temperature

Reefs less than 24" deep; freshwater planted
Compact Fluorescent
10 - 130
12 - 28 months
Longevity; high intensity; wide spectrum range;

May produce higher heat, may require a chiller to control Water temperature

Reefs less than 24" deep; freshwater planted; marine aquariums
Metal Halide
70 - 1000
6 - 18 months
Highest intensity; wide
spectrum range

Produce higher heat, may require a chillers to control water temperature; possible UV radiation

Reefs or freshwater aquariums more than 24" deep; photosynthetic corals and invertebrates

LED (Light Emitting Diode) Moon / Lunar Light
Light Emitting Diode)

Approx 1 watt
N / A
N / A Low wattage; recreates nocturnal
lighting conditions; great for viewing nocturnal inhabitants
Requires one unit per every 24"
of aquarium length
Reef or freshwater aquariums

Timing and Cycling

Most fish and aquatic plants need anywhere from 10 to 12 hours of lighting per day. Too much light can cause fish to develop behavioural problems and may encourage the growth of algae; too little lighting can cause plants to die off. It is critical to set up a regular and predictable lighting schedule. For very sensitive biotopes, it may be necessary to set up a timer. While fish from dark, tree-shaded environments do not require a "night light", fish native to open-water ecosystems can sometimes benefit from a whitish LED-based fixture that imitates moonlight. Breeders and professional aquarists may also adjust lighting times to mimic seasonal and lunar cycles; this can encourage temperamental fish to breed.


Choosing the light for your aquarium is a matter of personal taste, however, always use a lighting system specifically designed for your aquarium inhabitants needs. Simulating natural lighting conditions will greatly increase both survival and growth rates of your aquatic life.

Arcadia Classica 150w Double Halide Pendant
with LED Moonlight
Arcadia Light Enhancer Arcadia lighting
Arcadia OT2 T5 LED - 420 x 311 Arcadia marine luminaire light - 1000mm Arcadia OT2 LED Light - 420 x 280
Arcadia 3 Series (Click to Enlarge) Marine HQI Lamps 588 x 200