Written by Dan
When it comes to lighting your reef, there are several options you can choose from. Each one is going to have its pros and cons and a variety of price points. At the end of the day for most people it boils down to one of two questions; what do I want to grow, and what you I afford to buy.
In this article I will break down some of the basics of the most popular types of lighting options currently available in the hobby. We will look at the good, the bad, and the ugly where appropriate. In the end, you should have a strong enough foundation to understand the different options available in the hobby and how each has a place and a purpose.
Understanding the lingo
As with anything there is some common terminology that gets thrown around fairly loosely between people in the hobby and it is just expected that everyone knows what they are. When referring to reef lighting the most common terms are Spectrum, PAR, Kelvin and Nanometer (nm) are the four most important to know.
Spectrum
Most people when asked what a light spectrum is will say something like it’s the color of the light. This is true to a point. When discussing the color spectrums of a light though what we really mean is at what level does it produce all the different colors in the spectrum not just the color we see with the human eye.
This means how much reds, blues, and green light waves come off of the light. The amount of each can affect the photosynthetic rates of your coral and plants growth. Typically this is shown in a chart similar to the one displayed here where all the colors of the rainbow are shown across the graph and certain colors reach higher up the chart than others.
This is an important metric to know since different types of zooxanthellae and chlorophyll, these are the photosynthesis engines in corals and plants, are effected by different light spectrums. Most corals contain Chlorophyll A and will react best to Red, Blue, and Purple spectrums; but there are some that do best with greens.
Nanometer
Simply put, nonometers are a measurement for very small distances. This measurement is used when measuring light waves and helps provide a scale when we discuss PAR. Light you can see ranges from 400 to 800 nm. Higher than 800 is Infrared light IR like your remote control, lower than 400 is Ultra Violet UV light like a black light.
PAR
Photosynthetically Active Radiation, commonly known as PAR is a fairly standard way of measuring how strong a light is at different water depths. Par gives a numeric value indicating the intensity of the light in nanometers.
Ideal PAR will vary depending on the species you are keeping. A good range in a 19” – 24” deep tank would be to around 250 at the bottom of the tank and pushing 400 near the top. This range allows for a good mix tank setup. Depending on what you are growing you may not need the top or bottom end of that range and would focus on getting more of the tank to one of the two extremes to best benefit your coral.
Kelvin
Kelvin is the measure of light we would be most familiar with since it measures the color of the light when viewed by the human eye. Most lights have a Kelvin or K rating. For aquarium lights the higher the value the bluer it typically is, the lower the warmer and more yellow it is.
Higher K ratings have become much more popular in recent years. The logic to this is that most coral grows at a depth where the light if you were to dive to it is much bluer. Many people have also documented better growth and coloring on tanks after switching to more of a blue actinic coloration.
Types of light bulbs
Here is the heart of our discussion. What type of lighting options are there and which is best. The three types of lighting are defined by the three different type of bulbs used. Metal Halide, LED, and T5 Florescent. Each has its pros and cons and many people myself included have opted for using a combination of at least two of the three options.
Metal Halide Light Fixtures
Metal Halide or MH Lamps are a type of HID (High Intensity Discharge) light. This type of light produces a large volume of light via an electric arc created in the small discharge tube. Outside of aquarium usage these types of lamps are used in stadiums for sporting events, parking lots, as well as street lights. That should give you some indication as to how bright these lights can get.
The bulbs you would install in your aquarium are not going to be the same size as the ones lighting your favorite team’s field though.
To get all techy, the lamp works by passing an electrical current through a tube filled with a compound of halogen and electropositive elements. This is the halide. Once the halide warms it allows the current to easily travel in a large arc from one electrode to the other creating the bright white light.
A lot of hobbyists will tell you that halide lighting is an outdated technology but I don’t think that is the truth in all situation. Here are some pros and cons
Pros
Halides have the longest track record of all three options in keeping a successful reef tank.
They have been a staple in the hobby for longer than most of us have been in the hobby.
When combined with proper reflectors they can produce very dramatic lighting with high par values.
Halides produce some of the best shimmer effects out of all lighting.
These are very simple to setup, plug it in and go, maybe plug it into a timer so it cuts on and off on it’s on.
Cons
The biggest con for these lights is the heat they produce. They get very hot and will cause more evaporation than other lights. This can easily be countered with an auto top off system and chiller. Chillers are not one of the cheaper additions to a tank though.
These lights due require more electricity, and ultimately a higher power bill.
Many of the reflector and housing setups are larger and require more space. This means they are not as sleek and compact as most of the LED options.
This is one of the pricier option in both initial setup and ongoing maintenance and bulb replacement.
Finally the drop in popularity in lieu of some newer technologies does mean there are fewer options to choose from.
T5 HO Light Fixtures
Where Metal Halides have the longest track record of our 3 options, T5’s have the highest success rate of the three over the past decade. With the increase of their availability and popularity more and more people have been able to get into the hobby and have successful reef tanks.
The fixtures used are actually T5HO or T5 High Output not plain T5’s though from this point on we will simply refer to them as T5s as will most people. The difference is in the amount of lumens they produce which directly impacts how bright they are.
Fluorescent lamps ionize mercury vapor in their tube to create light. Over the years these lights have gotten more efficient and smaller. Over the past decade we have seen lots and lots of successful tanks running these lights.
Pros
T5s provide the most evenly dispersed light of the 3 options. This will reduce the shadowing effect caused by other more compact lighting options.
With enough T5 bulbs you can produce the same amount of light generated from a Halide lamp.
T5s have the least amount of sticker shock of the 3 options. They have a fairly reasonable cost of entry and are definitely the cheapest of the 3 in terms of initial cost.
T5s are plug and play. There are some options with choosing the light spectrum you want but the fixture itself will be very straight forward. Plug it into your timer and keep it moving.
You will see very little impacts on your tank due to the heat. Most heat can simply be mitigated with a small fan positioned to blow on the water.
Cons
Although the initial cost is much lower; over time, replacement bulbs combined with the added electric usage can cause these to be more expensive than an LED fixture if they are in operations for many years.
T5s do not produce the awesome shimmer effect that Halides and LEDs do. This shimmer is a big draw to the other two options and really give the tank the appearance of being at the bottom of the ocean.
T5s do loose in the cool factor next to LEDs. They do not offer all the cool options including color spectrum adjustability, smart phone or tablet app integration, intensity control, etc. These are all items we will list again in the LED Pros.
LED Light Fixtures
Light-emitting diodes or LED lights are the newest kid on the block. Although the original LED became a practical electronics component in the early 1960’s, it had limited uses other than remote controls and indicator lights until the past 20 years. In the past 10 they enhanced more than the original 50 years of their existence.
Like everything else the new cool and trendy products often have the biggest price tag. LED light fixtures can be an expensive investment. Over time though the fact that they have no bulbs to replace and use less electricity indicate they should be cheaper over time. LEDs also give you the most control over spectrum and intensity and most new options have integration with apps to easily adjust the settings from a tablet or phone.
Pros
LEDs can produce a tremendous amount of light with the smallest physical footprint over your tank.
The electricity consumption of LEDs is miniscule compared to its counter parts meaning they will save you money on your power bill.
LEDs are capable of creating shimmer effects in the water replicating metal halides and of course Mother Nature which is lacking with florescent.
Give the most controllability including spectrum, brightness, highly controllable day/night cycles and even weather patterns like cloud cover and lightning.
Cons
Because of the length of time LEDs have been in use in the hobby they do not have the proven track record of T5s and Halides.
In some ways the extent of configurability can be a disadvantage. Successful reef tanks thrive on stability and being able to go in and change light intensity and color regularly can have negative effects.
Although cheaper over a 5 year span, the initial cost of an LED lighting setup is much higher than the initial cost of the other options since a large portion of their expense is spread out in bulb replacements.
Mix and Match lighting setups
With each lighting option having pros and cons, it is no surprise that many modern reefers lean towards mixing and matching from the three. Personally I am using LED and T5s on my 180g in the living room. I have previously had great success on the same tank with metal halide and T12 florescent. T12s are T5s grandpa so to speak.
Both Metal Halide and LED can generate very high intensities of light and give off a great shimmer effect. LEDs have a much larger initial investment but Halides will cost more over time when replacing bulbs. These are the types of things you will most likely consider when deciding what lighting setup to use.
Conclusion
Ultimately it comes down to what you are trying to grow and what type of setup you have. Whether you have a canopy to hide your lighting or are looking for a clean minimal look with small LEDs it really just depends on what you want to grow. At the end of the day your true gauge of success is how well your corals are growing. If they are growing well does it really matter what type of light you use?
Are there any models of light you would recommend or steer others clear of? Let us know in the comments below.