We’ve all seen it before: an aquarium that simply seems to sparkle and radiate with its own internal brilliance, an array of colors like something from a world of dreams. And then we’ve seen its opposite: the drab, dark and cloudy aquarium where the living color seems all but washed out. While cleanliness has much to do with this effect, the cherry on top of it all is lighting!
The light alone can make the difference between an aquarium that everyone sees once and forgets, and one that etches itself in the memory as it draws the observer in with the power of its visual aesthetics!
While there are a few technical things to know about lighting, we will break it down in a simple way that makes it easy for you to determine how to choose an aquarium light that fits your needs and personal style.
Table of Contents
Why Is Lighting Important?
It’s easy for light to be an afterthought. It was certainly not on my mind when I was a kid with a few fish and an aquarium. I never thought about different ways to light the underwater world; I was just happy to see my fish!
But paying special attention to lighting has many benefits.
The most important benefit is actually personal; to the observer, the proper lighting brings out the colors in ways that are dramatically different than its poorly lit counterpart.
Besides the beauty of the aquarium, lighting also affects the way that plants grow, the health of the fish, and the presence or absence of unsightly algae growth.
Plant Growth
You may have heard the term “low tech” and “high tech” in reference to aquatic plants. This is a fancy way of classifying them in relation to their required maintenance; low tech plants are fairly easy to grow and maintain. You can probably guess what high tech means; it’s the other end of the scale, plants that require more attention and special assistance from the aquarist to grow.
High tech plants generally grow faster, and low tech plants grow slower. The high tech plants will need higher intensity of light, and the low tech plants require less. If you’re a beginner, consider using low tech plants such as anubias, Amazon sword, java fern, sagittaria, cryptocorine or bucephalandra. These are not as needy when it comes to special lighting, and they allow you to “get your feet wet,” so to speak, as you gain experience as an aquarist.
Fish Health
The main health issue for fish in relation to light is stress. Imagine trying to go a full 24 hours with full lighting at all times, no changes, and no periods of darkness. How could you relax properly? How would your eyes feel after such exposure? The same goes for our fish. Too much light for too long a period can raise levels of stress which, over time, can cause other health issues. On the other hand (or fin?), total darkness for prolonged periods of time can also cause stress.
Given that you have a life too, it’s highly unlikely the fish are going to be in perpetual darkness. But you don’t want to forget to turn out the lights every night. Keeping a regular pattern benefits their circadian rhythm, which is important not to disrupt regularly. Keeping a predictable pattern of light and darkness gives them time to rest, entering a state akin to that of sleeping.
Algae Growth
Algae and plants compete for the same nutrients and light. In the absence of plants, intense light can encourage the growth of algae. If you do have plants, this can stave off much of the algae growth due to the plants winning the food competition.
In some situations where you have high intensity light, particularly for fast-growing (high tech) aquarium plants, you also should be sure that enough CO2 and nutrients are being supplied for the plants; otherwise, you may have a situation where the plants cannot efficiently utilize the available nutrients, and the algae starts to win the food competition and propagate.
Important Units of Measurement
Now that we’ve established that light is important, what is the “language” of light that we need to know? Here are the core vocabulary words for you in this subject that will help you choose the best lighting for your aquarium.
Intensity (Lumens)
The intensity of light means very basically, how bright is the light? This can be measured in either watts or lumens. Watts are a measurement of how much energy is consumed when the light is produced; however, measuring in lumens allows us to compare different types of lights that may be more or less energy efficient.
You’ll be pleased to know that most fish are not going to mind much about light intensity, within reason. What they care about is periods of light and darkness.
Plants, however, do care about intensity. The easier, slow-growing plants can do with a light intensity of around 15-25 lumens per liter of water in the aquarium. The more advanced, fast-growing plants may require something around 50 lumens or more per liter. It’s important to research your particular plants to determine what light is best for them to flourish.
Color Temperature (Kelvins)
Color temperature is measured on a scale which ranges from warm colors (yellow) on the lower end to cool colors (bluish-white) at the upper end. It is measured in kelvins.
Color temperature is made up of red, green and blue (RGB) light. At different times of day, different colors stand out among the rest.
Natural daylight color temperature ranges between about 5,000 and 6,500 kelvins as the sun crosses the sky. Throughout the day, however, our world is exposed to approximately equal levels of red, green and blue light. Blue and red light particularly are important for most plants, as you can see that green is usually the color reflected back from the plant and not absorbed. Possessing a light that includes equal, or mostly equal, parts of all three colors is ideal for plants’ physiological processes which include their colorful appearance.
Beam Spread
Simply put, this refers to the fact that light becomes less intense the further the receiver is from the light source. It also becomes less intense the greater the angle of the light from the light source. An extreme example would be a laser, which has a very narrow beam spread and can therefore shine intensely for enormous distances.
But there’s no need to get too caught in the weeds with this concept. The main thing to remember is that the dimensions of your aquarium makes a difference to the plants’ ability to utilize the light. Plants that are off to the side or in a corner will not get as much benefit from the light as those in the center. Plants at a lower level in the aquarium won’t benefit as much as those which are higher.
If you have plants which require more light, place them in the middle or at higher ground. The lower tech plants can be placed at the further edges or at lower levels, as space requires.
PAR (Photosynthetically Active Radiation)
Sounds very technical, doesn’t it? Well, it is, but let’s make it simple. This term refers specifically to light with the proper wavelength to allow photosynthesis to occur in plants.
The PAR range is 400-700 nanometers (nm); this is the wavelength that photosynthesis can use.
While this is not as important for a simple planted aquarium, it becomes much more important if you include a coral reef. If you’re a beginner and simply using a freshwater aquarium with plants, this is less important so long as your plants are thriving under the earlier considerations of light intensity, spectrum and spread.
If you still are encountering problems with your plant life, this may be something you want to measure using a PAR meter. You will see that it makes a big difference whether a plant is placed in the center or toward the edges of an aquarium. The type of plant or coral will differ among themselves widely in terms of how much PAR is needed for healthy growth and coloration.
Types of Lights
Now that we know the basic language of light that we’re dealing with, how can we apply this practically? The type of lights normally used in aquariums can be summarized in three categories.
Fluorescent Lights
This most basic kind of lighting is also the cheapest. Both standard and compact (more energy efficient) versions are available. They usually do not have much customization capabilities, but they can be placed on a timer so that you don’t have to remember to turn on or off the lights. They are offered with different color spectrums, including full spectrum to imitate daylight; however, they aren’t as flexible as LED lights in customization or change throughout the day.
They last approximately 12-24 months before needing to be replaced.
Take note that they also put off heat, which is important to consider when determining how much heating power is needed to bring the water temperature to the proper levels.
Halide Lights
These are particularly good for saltwater aquariums, or any large aquarium for that matter. They are high intensity lights which can penetrate to great depths while bringing out the vividness of color. Halide lights also tend to produce an attractive shimmer effect on the tank, a subtle dance of light and shadow that emphasizes life and energy within the water.
A potential downside is that it produces a significant amount of heat, which often requires a chiller to also be installed in the aquarium to keep the water from overheating. These are generally large lights and require replacement approximately once a year.
Halide lights are a bit pricier than other options, but they can be an excellent choice particularly for a reef tank. Some prefer to even use the halide light in combination with fluorescent lighting.
LED Lights
If you’re looking for customization, look no further than the LED light. These can offer a wide spectrum of color temperature, ideally even the full spectrum with near equal levels of red, green and blue. Unique to LED, these can alter color levels throughout the day to imitate morning, afternoon and evening. Many have pre-programmed options for this, or you can customize it based on your particular aquarium needs. They also can be dimmed or brightened in intensity.
LED lights don’t heat the water like the other options. They are energy efficient and long-lasting, usually needing to be replaced once every several years.
Conclusion
Lighting your aquarium with appropriate intensity and color temperature, while paying some attention to beam spread and PAR, will highlight the aesthetics of your water wonderland. It will also bring comfort to your fish and prosperity to your plants.
Once you’ve chosen the right light for your needs, all you need to do is program the timer to give your fish the recommended 10-12 hours of light each day. If you have high tech plants, you may want to do the recommended 12 hours. If you have no plants, you can reduce lighting time closer to 8 hours, which also helps stave off algae growth.
Once completed, your aquarium now radiates in all its color and detail. All your hard work has paid off! Kick back, relax, and enjoy the beauty of your underwater paradise.