Aquariums are miniature living ecosystems. Properly designed systems have filtration, space, water flow and several other factors included in the setup. Aquariums have a function, a purpose, and a set of methodical constructs used to accomplish the goal of providing a healthy and thriving environment for their inhabitants. But let’s be honest: the best part of aquariums is looking at them. Hobbyists want their aquariums to shine, sparkle and showcase their beloved aquatic pets.
Reef aquarium inhabitants are incomprehensibly diverse. The sheer number of different organisms available that are well-suited for home aquaria are too vast to comprehend. The hobby tends to focus on a few select groupings of organisms for aquariums, most notably fish, corals and some crustaceans. While these groupings dominate the hobby, a multitude of other organisms play an important role in reef systems and home aquaria. Some examples of other important organisms are mollusks (including snails and clams), echinoderms (including sea stars and urchins) and macroalgae. All of these items can be showcased and highlighted in a reef aquarium. Often the key to really seeing something is to provide the right amount of light for it.
1. Blue Light and Corals
The idea of “lighting up corals” with blue light is certainly nothing new. For more than a decade, reef aquariums have featured a standard set of two lights: white and blue. Hobbyists have been using “white light,” which has a broad spectrum, to illuminate their aquariums for viewing as well as for producing energy for their inhabitants’ photosynthesis and growth. The blue light added to most reef aquariums can also help with growth and photosynthesis, but it is primarily used to cause a biological response (termed actinic) in the animals, which usually involves a response to produce colors.
Blue light is not just one color – it can range from about 410 nanometers to 490 nm. Some manufacturers will produce a 420-nm bulb and a 450-nm bulb, while other manufacturers will make a bulb that has many peaks in the 400s. An old adage in reefkeeping is that if you want to grow corals, give them a lot of white light, and if you want corals to glow, give them a lot of blue light.
In addition to adding blue light to the broad white spectrum, many hobbyists like to use blue light as the only light for viewing the fluorescent effects of corals. Coral fluorescence is an emerging part of the hobby and science. Fluorescence occurs when the coral tissue receives energy at one wavelength (meaning one color of light) and then gives off or produces light at a different wavelength (giving off a different color). While certainly an unnatural look, it is one that many people find appealing. Many corals appear to glow when under blue light, and they will frequently produce green, orange or red light, which is emitted and seen.
2. Green Light and Corals
An overlooked aspect of reefkeeping is the effect of green light on corals. Green light can produce similar effects as when blue light is used. Some corals have proteins that produce fluorescent light when in the presence of blue light, and some corals have proteins that produce fluorescent light when exposed to green light. In other words, by illuminating your aquarium with blue light and without green light, you may not be seeing all of the colors and patterns in your corals. Often a coral that looks rather drab in blue light will shine with striking colors when under green light.
3. Think Outside The Box
A creative and unique way to add lights to an aquarium is to add lights outside of an aquarium. Nearly all reef setups feature livestock contained within the tank, and therefore light is never needed outside the tank. However, some aquariums feature plants, for example, that extend beyond the basic aquarium framework. An example of this is an aquarium featuring mangroves. These aquariums have light fixtures well above an aquarium to provide light for the plants. Low-energy bulbs, such as compact fluorescent bulbs, work wonderfully for this application. These bulbs can simply be hung above the aquarium or used in an elegant fixture, adding to the room decor. This can be appealing, as it creates unique external focal points of interest. Suddenly people aren’t looking into the aquarium but are looking around the aquarium.
LED (light-emitting diode) lighting systems have become more popular in recent years, and we have seen some unique high-powered spotlights enter the hobby. These lights can be used to direct a beam of light down onto a select animal or area. These lights allow you to focus the light (and the attention of other hobbyists) on something without illuminating the surrounding area. These lights can be the primary source of light in nano aquarium setups, but in larger systems, they can be used to selectively illuminate an area of focus. If you have an aquarium with one key species, such as an anemone with a pair of hosting anemonefishes, a spotlight allows you to provide direct bright light onto the anemone. Spotlights can also be useful to produce clean and clutter-free systems. Rather than having a large light fixture covering the tank, a spotlight can be a small, discreet item, while still producing a serious punch of energy.
Very few reef aquariums take advantage of natural sunlight. Having an aquarium near a window can be a blessing. While some aquarists worry about algae problems and high heat from direct sunlight, there are hundreds of wonderful examples of aquariums utilizing sunlight. Natural sunlight can fuel the growth of many corals. Also, it is completely logical to assume that natural sunlight would stimulate healthy behaviors in many fish and invertebrate species. Aquariums lit with sunlight have a beautiful shine to them and certainly seem bright to the viewer. One constraint with sunlight is that for many aquariums near windows, you’ll only get partial light or light for a certain part of the day. For this reason, nearly all aquariums utilizing sunlight also use sources of artificial light.
Moonlights began as a funny little side gimmick in the hobby 10 years ago. Today, they are standard on nearly all reef aquarium fixtures. The moon itself does not produce light. Rather, the moon reflects light off of it from the sun. Moonlights are said to have a few purposes, including stimulation of lunar cycles (for things like coral spawning) and for dissuading fish from jumping from an open-topped aquarium. However, the purpose of a moonlight is to make your tank look cool. Much like having blue and green lights for corals, moonlights illuminate an aquarium with a unique spectrum to produce an appealing display. Moonlights for the aquarium are usually white but dim, just as you’d expect to see at night under the moon. Other manufacturers make moonlights that are dim but blue in color. These moonlights are thought to be more in line with the color rendition you’d find below the ocean’s surface. Other manufacturers combine the two, offering lights with both blue and white bulbs combined together. The dim light and slight glow found under moonlights are intriguing and give hobbyists another perspective on their aquariums.
Many small invertebrates spend the entire day hidden in the rock and sand. These animals come out at night, and that is when a reef is truly alive. Moonlights allow hobbyists to view these animals and see their behaviors as they scurry around the substrate.
The 8 Lighting Types and Their Effects
7. Underwater Lights
Underwater lights have two main purposes. One, which is uncommon, is to provide a light source close to an animal to give it energy. Underwater LED lights can be a great way to place lighting down in the aquarium near an animal. One example of this is making a little rock arch with the LED lights hidden behind the structure. These lights can be directed toward something like a clam, eliminating the need for high-powered lights above the tank. A word of caution: underwater lights only work when their lenses are clean and clear of algae.
A second and far more common use of underwater lights is for aesthetics. Underwater lights (mostly homemade) were uncommon in the late 1990s and never really took off. But in the 2000s, a few companies started to manufacture underwater lights, and they are slowly entering the hobby. Many aquarists view them as unnatural and avoid them, while others like the artistic flare they provide. Underwater lights are available in a wide range of colors and can be used creatively to produce interesting and ever-changing displays.
Lighting is critically important in a reef aquarium. The proper wavelength and quantity of light are both important for providing the energy for photosynthetic organisms that dominate coral reefs. In addition, a wide range of aesthetic concerns influence lighting considerations. Aquariums are functioning systems with biological processes at play, yet at the same time they serve as interesting displays.
8. Cabinet Lighting
The first seven lighting options discussed in this article help bring attention to the inside of an aquarium. Some aquarists want to bring attention to their entire aquarium, including its cabinet stand or canopy. Some aquariums feature lights inside cabinets that intentionally shine out toward the viewer. Some have lights behind an illuminated panel, such as etched glass or stained glass. These lights help to make the aquarium a large piece of artwork in the home. Some people like to blend their aquarium in with the rest of the room, allowing the livestock to draw people’s attention. However, other people prefer to bring attention to the entire aquarium by illuminating the surrounding structural system. With all these approaches, personal creative skills can make an aquarium uniquely your own.
Often the key to producing a stand-out system is to draw attention and focus to something outside of the box, literally.
Adam Blundell is an expert marine biologist currently serving as the Director for the Aquatic and Terrestrial Research Team, and he teaches at the University of Utah. Adam also speaks to many clubs, organizations and public aquariums.