Why is lighting important for aquariums? In its most basic role, aquarium lighting
allows hobbyists to observe aquarium inhabitants. But more importantly, proper
aquarium lighting provides vital energy to photosynthetic plants and animals. As
the primary light source (and in most cases, the only light source), proper
aquarium lighting is essential for any system that contains photosynthetic
organisms such as plants, anemones, or corals. Lighting also influences fish
behaviour and physiology and is vital for the overall health and well-being of
the entire aquarium.
With so many different types of light bulbs and light
fixtures, how do I know which one is right for me? The first step in selecting the appropriate
light fixture and the corresponding bulbs is to identify use. Aquarium lighting
has two main uses: a general aesthetic one and a functional one to sustain the
biological processes that occur in the aquarium. To narrow down your selection,
identify your needs as well as the needs of your aquarium inhabitants and
determine what you want to achieve in your particular aquarium setup.
Which
lighting system is recommended for fish-only, planted or reef aquariums? The specific lighting
requirements may vary from one aquarium to another but the following
recommendations serve as a good general guideline when selecting a lighting
system.
Fish-only Aquariums:Fish, artificial plants, decorative wood and/or
ceramics. Recommended Lighting System:
Standard or a
Compact Fluorescent system.
Freshwater-planted
Aquariums:Fish, live plants,
decorative wood and/or ceramics. Recommended Lighting System:
Standard Fluorescent,
T-5 HO,
VHO,
Compact Fluorescent or
Metal Halide/HQI system.
Saltwater Reef Aquariums:Fish, invertebrates, corals, and liverock. Recommended Lighting Systems:
T-5 HO,
VHO,
Compact Fluorescent or
Metal Halide/HQI system
How do
I choose a light fixture that will provide enough light for my aquarium
inhabitants? When we are interested in
providing light conditions necessary to sustain life, we are most interested in
the intensity of a bulb. In general, fixtures that utilize higher wattage bulbs
tend to have greater light intensity. Therefore, the total wattage of a light
fixture serves as a good general guide when calculating lighting needs. Keep in
mind that many factors such as water depth, water clarity, and height/location
of the light fixture affect light intensity. To compensate for potential
light-loss, select a fixture on the higher end of the recommended
watts-per-gallon range. Lighting requirements will also vary depending on the
species you are keeping, so it is essential to research the specific lighting
requirements of each species.
Fish-only Aquariums- A lighting system with a total output between 1 to
2 watts per gallon should be sufficient to simulate a day-night cycle. Because
the requirements of a fish-only aquarium are forgiving, you can choose the
spectrum of bulb that best suits your preference. Avoid the use of standard
hardware store bulbs, which promote the growth of brown algae.
Freshwater-planted
Aquariums- Depending on the
particular plant species you plan to keep, as well as the depth of your
aquarium, you will need a lighting system with a total output between 2 and 5
watts per gallon. Full-spectrum bulbs (also called daylight bulbs, grow bulbs or
plant lights) designed specifically for aquarium-use ensure healthy plant
growth.
Saltwater Reef Aquariums- To correctly light a reef aquarium that is 24" deep
or less, use a lighting system with a total output between 4 to 8 watts per
gallon. You can relax requirements significantly by choosing corals and
invertebrates that require low light levels, or non-photosynthetic
invertebrates. The light requirement of corals and invertebrates varies
dramatically depending on the species and the location of the reef they inhabit
in the wild. Most corals that inhabit ocean depths between 15 to 65 feet have
adapted to intense light conditions or hide themselves within the reef for
safety. While corals found at depths below 65 feet are non-photosynthetic or
have adapted to extremely low light conditions. Many reef hobbyists prefer the
intense lighting provided by
metal halide fixtures utilizing 10000°K bulbs in combination with blue Actinic
bulbs
How do I calculate light output of a fixture in
watts-per-gallon? To calculate the number of watts-per-gallon an
aquarium receives from a light fixture, simply divide the total wattage of the
light fixture by the number of gallons of the aquarium. For example, a 55-watt
fixture used over a 29-gallon aquarium will provide its inhabitants with
slightly less than 2 watts of light per gallon. While this amount of light is
perfect for fish-only aquariums, it may not be adequate for most photosynthetic
reef inhabitants.
How long do I keep the lights on my aquarium? In general, the length of time your aquarium
lights are on (photoperiod) should simulate the natural day and night cycle. A
photoperiod of 10 to 12 hours of light a day will provide sufficient light
energy for photosynthetic plants and animals, but depending on the type of
aquarium and the light requirements of the aquarium inhabitant, photoperiods can
be slightly longer. The easiest way to maintain the proper photoperiod in a
consistent manner is through the use of aquarium timers.
Do I need a glass top or canopy with my light fixture? The use of a
glass top or canopy is recommended for all light fixtures, especially
fixtures with exposed bulbs or without a protective lens or splashguard. Not
only do glass canopies provide additional stability for your light fixture, they
also protect the light bulb and fixture from condensation and splashing. Contact
with water can damage the unit or cause serious injury.
How
often should I replace the bulbs and why?
The intensity of a bulb diminishes over time. Even though the bulb will still
light up, it may not be emitting the necessary spectrum or intensity to support
healthy growth. In many instances, the diminished light output can encourage
nuisance algae growth.
Incandescent Bulbs- Replace every 2 to 4 months. Standard
Fluorescent Bulbs-
Replace every 6 to 18 months depending on ballast type. VHO Fluorescent
Bulbs- Replace every
4 to 18 months depending on ballast type. T-5 HO Fluorescent
Bulbs- Replace every
16 to 24 months. Compact
Fluorescent Bulbs-
Replace every 14 to 24 months. Metal Halide Bulbs- Replace every 6 to 18 months.
