Vivarium Lighting 101
Everything you need to know about illuminating a vivarium!
This page is part of our informative vivarium building series of articles.
Intro Articles: Vivarium Building Checklist | Basics of Vivarium Lighting | Custom Background DIY
Full Articles: Vivarium Construction 101 | Vivarium Lighting 101 | Vivarium Construction 102

Common Types Of Vivarium Lighting: Jungle Dawn LED, "Corn" LED, Compact Fluorescent, T5, T8, T12
 
Introduction
Selecting lighting for your vivarium can be daunting at the beginning. There is so much information about lighting online, that it can be difficult and confusing to figure out just how much, and what type of lighting you need. This article will explain both the basics and more advanced aspects of what you'll want to keep in mind when selecting the lighting for your vivarium. Before we can get too far into which bulbs you should consider, we need to quickly cover the basic lighting lingo that will be used to help figure it all out.
 
Lumens (Brightness/Intensity)
"Will the light be bright enough to the human eye?"
 
Lumens
A lumen is the unit of measurement for the total amount of visible light emitted by a source. Most bulbs are rated for lumen output (often abbreviated as "lm") by the manufacturer, to notify the consumer of "how bright" a bulb will appear to the eye. Lumens add/stack, meaning if you have two 1000 lumen rated bulbs in a fixture, the total luminous emittance will be approximately 2000lm. The term for metering how much light is incident on a surface is called illuminance, which means lumens per square meter. (lux for short) Lumen ratings of a bulb are very important in vivarium building because this measurement will help us determine whether or not a display will look sufficiently bright enough to human eyes using a specific light source.
 
A simple light meter is a useful tool for spot-measuring illuminance in a live vivarium. Knowing exactly how much light is incident on a surface can help compare your vivarium to others, using an "apples-to-apples" unit of measurement that's commonly used in the hobby.
Kelvin (Color Temperature)
"Will the light source represent color within the vivarium correctly, and will the chosen spectrum grow plants successfully?"
 
Kelvin Color Temperature For Vivariums
Click to enlarge
Kelvin is the unit of measurement for the overall color temperature of a bulb. Unlike the lumen unit of measurement, Kelvin ratings do not add/stack. (If you use two 5000K bulbs, the Kelvin rating remains 5000K) Kelvin helps us to get a rough idea whether or not the spectrum of light will allow for a plant to grow under the source, and whether or not the enclosure will look natural to the human eye. When selecting a vivarium light bulb, you want to stay in the 5000-6700K range for color temperature, since natural daylight spectrum is 5500-6500K (depending on viewing standards). All full spectrum fluorescent and LED bulbs in the appropriate color spectrum will grow all commonly available vivarium plants with ease, assuming the bulbs are sufficiently bright. Bulbs in the range of around 5000K appear warmer to the eye, whereas bulbs rated much above 6500K can look colder. The combination of measured illuminance and color temperature are suitable gauges to determine which bulbs you'll need to make your vivarium appear beautiful to the eye, as well as give the builder a general, but effective idea of whether or not plants will have sufficient light to thrive in a vivarium.
PAR & Spectral Energy Distribution
"Exactly how efficiently will the light grow plants?"
 

PAR (Photosynthetic Active Radiation) values are the most accurate unit of measurement to determine a bulb's efficiency in growing a plant specifically. PAR measures the spectral range of radiation from 400-700 nanometers, which is the same range plants utilize for photosynthesis. This unit of measurement is frequently used in both agriculture and the aquarium hobby, since reefs and certain underwater plants require a significantly higher PAR rating than any common vivarium plants will for long term success.
 
As time moves on, more bulbs may be available to the vivarium building community that include relevant PAR ratings, but at the moment this unit of measurement is still fairly uncommon to the hobby.
 
With that in mind, PAR is used for determining plant growth efficiency only; and does not consider how a light source will look to the human eye when applied to a vivarium & it's inhabitants. For example, many agricultural & aquarium lights that have excellent PAR values would look unnatural if applied to a vivarium, due to the extremely high intensity of blue & red visible light within the 400-700NM wavelength. So while PAR is the best gauge to determine how efficiently a light source will grow plants specifically; it's not the best gauge to determine which bulb will work best for your vivarium, since visible, naturally accurate light is critically important to the look of the finished product. To determine how accurately a bulb will make things appear to the human eye, we'll have to keep color temperature in mind as we turn to color rendering index.
Inverse Square Law
"Is my vivarium too tall for this light source?"
 
Inverse square law applied to vivariums.
The inverse square law applied to vivarium lighting is important because every time the distance from a light source doubles, the light is distributed over four times the area. Therefore, any surface that's twice the distance from the light source will receive only 1/4 of the measurable illuminance. (1/4 as bright!)
 
The inverse square law is why a vivarium's height is so critical in determining a vivarium light source. For example, a 24" tall enclosure would meter up to 400% brighter at the bottom than a 36" tall enclosure would using an identical light setup, due to the extra foot of height. Understanding the inverse square law is critical when building vivariums over 24" tall, since in our experience, fairly bright lights may be necessary to fully illuminate such a deep a vivarium. If an enclosure will be over the 24" mark, it may be worth considering unidirectional spot LED lighting, T5HO, or other fluorescent lighting with a fixture that can concentrate as much light downward as possible. (Higher wattage 32W CFLs with deep dome fixtures fit the bill nicely, if heat isn't as much of an issue!) Selecting a light fixture with a good reflector is critical, when using fluorescent lighting. Since most LED lighting is unidirectional, a good reflector isn't as important as it would be when using omnidirectional fluorescent bulbs. We have a chart near the bottom of the article to help you decide which bulbs & fixtures would fit your build specifically.
Color Rendering Index & "Full Spectrum" Light
"Will the contents of my vivarium look naturally accurate under this light?"
 
Color rendering index is an older method of determining how accurately a light source can display the color appearance of an object. Often referred to as "color accuracy", CRI is typically measured from 0-100 percent; indicating how accurate a light source is at displaying colors compared to a reference light source of a similar color temperature. Many manufacturers include CRI rating information with bulbs, making it a fairly usable gauge of how natural things will appear to the human eye, if the correct color temperature is used. Because CRI is completely independent of color temperature (kelvin), it's important to 1'st select a bulb in the appropriate color temperature range before considering CRI. In other words, a 4000K bulb may have an 80+ CRI rating, but would not be the correct color spectrum of light for a vivarium. (Between 5000-6500K is ideal, as explained above) The term "full spectrum light" is used often these days, but it actually has no scientific definition. In fact, it's a marketing term that essentially labels a bulb as one that emulates natural light. (Or in plain English, it's got a "good" color rendering index!) If a bulb is labeled as "full spectrum", but doesn't include it's exact CRI, you've at least got a general idea that it should be rated with a fairly high (80+) CRI. Anything in the 80+ range is considered to have a good CRI, and bulbs rated 90+ have an excellent CRI.
Lighting Types
This next section will discuss all the commonly available bulb & fixture types, with the advantages & disadvantages of each described in detail.
 
Compact Fluorescent Bulbs
The most common vivarium lighting solution used today
 
Vivarium Compact Flourescent Bulb
Standard Compact Fluorescent Bulb
 
Compact fluorescent bulbs are available in a very wide range of shapes, sizes, wattages, and color temperatures. Most sizes easily fit into the most inexpensive (and common) light housings. These bulbs are available with or without an integrated ballast, with the former being most common. Without an integrated ballast, the bulbs are more efficient, but significantly more expensive. (The cost usually outweighs the efficiency benefit!) The main disadvantage to a CFL is heat, so those keeping heat-sensitive species should keep this in mind. Most possible heat issues found when using higher wattage bulbs can be controlled by using deeper light fixtures to keep the bulb further from the enclosure. We've also used rubber feet purchased at a hardware store to lift a fixture a little higher from the top while keeping it looking neat. Hanging the lights above the terrarium works great, but admittedly it's at the cost of aesthetics. Plant growth compact fluorescent bulbs average roughly 60-70 lumens per watt.*
 
When To Use Compact Flourescent Bulbs
We'd suggest using CFLs when working with non-temperature sensitive species, with vivariums ranging from 8-36" wide. Since flourescent fixtures become very inexpensive at the 4-foot mark (the most common size), using compact flourescent bulbs on terrariums over 36" wide can be cost-ineffective in comparison. A good reflector becomes more important with taller enclosures (24"+), as reflecting a CFL's omnidirectional light downward is critical for these bulbs to perform well.
Compact Fluorescent
 
_________________________________________________________________________________________________________________
 
Fluorescent Tubes
The best option to illuminate a wide enclosure, or many smaller enclosures in a row
 
Types of fluorescent bulbs used in terrarium & vivarium building
T5 Bulbs = Most Efficient     T8 Bulbs = Efficient            T12 Bulbs = Least Efficient              
 
There are three types of commonly used tube fluorescent bulbs. In order of most efficient to least efficient: T5HO, T8, and T12. The number following the "T" is a designation of width, by 1/8 inch increments. (T5 = 5 eighths / T8 = 8 eighths / T12 = 12 eighths) These bulbs have some of the widest ranges of availability for sizes and color temperatures. Each bulb type comes in a few different lengths and wattages ranging from 12" all the way up to eight feet for commercial applications. Bulbs of the same length & style are generally the same rated wattage, in the herpetoculture hobby. (So any common brand of 24" T8 bulb we offer will fit any 24" T8 fixture we offer + so on.)
T5 bulbs are roughly 95-100 lumens per watt / T8 bulbs are roughly 75-80 lumens per watt / T12 bulbs are roughly 55-60 lumens per watt *
 
When to use Fluorescent Tube Lighting
Standard "tube" fluorescent bulbs are most commonly used with wide enclosures, when placing many terrariums in a row, or with "rack style" breeding setups. For those situations, fluorescent lighting is often the most cost effective long-term solution, when an average/moderate amount of heat isn't a concern. The 24" and 48" widths of bulbs & fixtures are by far the most common, which usually makes them the most cost effective. Nowadays, the least efficient bulb most enthusiasts use is a T8, with T5HO being the best bet in most situations. Inefficient T12s are occasionally used (and work fine for shorter enclosures), but are being phased out by many manufacturers as it's replaced with newer tech.
 
Vivarium T5HO Bulb Efficiency & Cost ChartVivarium T8 Bulb Efficiency & Cost ChartVivarium T12 Bulb Efficiency & Cost Chart
 
_________________________________________________________________________________________________________________
 
Vivarium-Appropriate LED Bulbs
The most efficient, longest lasting, and often best looking option to illuminate a vivarium
 

An 11W Jungle Dawn LED Vivarium Light Bulb
 
With the highest efficiency rating and lowest heat output of any bulb in the hobby, it's no wonder LED lighting is quickly growing in popularity. LED bulbs are improving every day, and becoming less and less expensive as time goes on. Unfortunately prices are still fairly high compared to fluorescent lighting, but the big advantages are a lower temperature (actual temperature, not color temperature), efficiency, and brightness. Higher quality LEDs produce very little heat in comparison to all other lighting types, and are most commonly unidirectional. Jungle Dawn vivarium-specific LED bulbs have a combo of two different color temperatures (which is ideal), high quality LED diodes, and are a great value considering their performance. If heat is a concern, Jungle Dawn LED bulbs are an excellent alternative to fluorescent lighting.
 
When to use LED lighting
Jungle Dawn LEDs are one of the most versatile solutions, due to the low heat output, low wattage, bright light output, and ideal color temperature. Since they are unidirectional & available in a wide variety of sizes, they are well suited for any terrarium ranging from 12" to 36" high. Fixtures for these are currently limited to 36" wide (Exo Terra's largest compact top), but using two hoods per enclosure is common practice for wider enclosures. Breeder customers & commercial clients often use custom "side mounted fixtures" in rack shelving, and for custom installations. These aren't the best solution to those building on a tight budget, or for those working with shorter terrariums under 13" high.
 

We are not describing cheap Chinese generic LEDs. In our testing of three different types of "corn cob" style LED bulbs, none produced significantly less heat than a low-wattage CFL, and one of the three bulb types we tested began melting in it's deep-dome housing before an hour of use. (Photo) If you are going with LEDs, we use & recommend Jungle Dawn LED lighting!
Vivarium LED Bulb Efficiency & Cost Chart
 
_________________________________________________________________________________________________________________
 
Overall Lumen-Per-Watt Comparison
 Compact fluorescent bulbs average roughly 60-70 lumens per watt *
 
 T5 bulbs average roughly 95-100 lumens per watt *
 
 T8 bulbs average roughly 75-80 lumens per watt *
 
 T12 bulbs average roughly 55-60 lumens per watt *
 
 LED bulbs average roughly 80-105+ lumens per watt **
 
* Non-scientific information compiled & averaged from a variety of manufacturers & light-testing sources. For informative use only. HO Bulbs use more energy, and produce more light.
** The lumens per watt range of LED bulbs is improving rapidly as technology gets better. Generally speaking, the better the LED, the more efficient it is at producing light per watt.
Keeping Priorities Straight
There are 4 basic & easy to understand goals to keep in mind when choosing a vivarium light source.
 
Goal #1: Illuminate the vivarium with accurate, natural looking light to ensure inhabitants, plants, and decor appear natural to the eye.
A naturally accurate light source is critical to the overall appearance of a vivarium. Bulbs with a color temperature similar to daylight (5000-6500K) are ideal. (+ also grow plants!)
 
Goal #2: Ensure light can penetrate to the base of the enclosure for a nice looking, well illuminated display that'll support flora life top to bottom.
Lighting must be bright enough to illuminate the enclosure top to bottom. Remember: The taller an enclosure is, the brighter your light source will need to be.
 
Goal #3: Ensure the vivarium's lighting will sufficiently grow terrarium plants long term.
Bulbs in the correct color temperature range (5000-6700K) will grow plants in the vivarium setting flawlessly. PAR ratings can also be used for determining photosynthetic efficiency.
 
Goal #4: Don't spend more than necessary on an overkill lighting solution.
Plants are relatively easy to grow in a humid glass box, so you don't need super-bright, super-expensive lighting for it to look & work great. (Plus super-bright light can look unnatural)
 
 
Choosing a Vivarium Light Source
There are two ways to go about selecting a light source, with one requiring a much better grasp on the above concepts than the other. We want to offer the most precise information we can, but we'd hate to scare off hobbyists by only presenting the most technical (i.e. difficult) option. Considering the easier option works exceptionally well for most common size terrariums, you can use information from either of the below methods to get your vivarium illuminated quickly, easily, and effectively.
 
Selecting A Vivarium Light Source
 
"The Technical Way"

Technically the most accurate method to select a more complex lighting source.
This method is most useful to those illuminating a very large or very unique enclosures, in our experience. This way of looking at different light sources involves balancing CRI, PAR, Kelvin, and Lumen output to determine exactly which solution will work best for a particular enclosure. In all, Kelvin & CRI would be referenced to ensure the vivarium would appear accurately compared to natural light, Lumen & Illuminance ratings would be used to ensure the enclosure will appear bright enough to the human eye, and PAR ratings would be used to check photosynthetic efficiency to ensure ideal plant growth. The inverse square law should kept in mind for all enclosures that are significantly taller than they are wide/deep, and for enclosures over 24" tall to ensure enough light penetration within the enclosure. Lumen & PAR meters are available & useful for this purpose, but this usually isn't the most practical option to determine a vivarium lighting solution for a casual hobbyist!
Selecting A Vivarium Light Source
 
"The Simple/Easy Way"

A simple, accurate, and proven way to get it right without blowing your wallet & losing your mind.
The easiest, most common, and most practical way to select a vivarium light source is by selecting a bulb in the 5000-6500K color temperature range, and ensuring it'll have enough lumen output to brightly illuminate your vivarium to the floor level for visibility. This has been the easiest, simplest, and most reliable way to choose a vivarium light source for years, and it's still the most common method used by hobbyists today. For nearly all common sized vivariums, inexpensive fluorescent or LED bulbs are available to meet these goals perfectly for a great looking, long lasting, efficient lighting solution.
 
If you don't have much experience as to what's bright enough for a specific size enclosure, the next part of the article will provide examples of appropriate lighting setups applied to all common sizes of terrariums.
Real-World Examples + Making The Decision
With the academic stuff behind us, lets apply the info towards selecting an appropriate vivarium lighting solution.
With all the above lighting information in mind, we created the chart (below) to help make choosing a light source as easy as possible for common vivarium sizes. Although every vivarium's requirements can vary, the shown options are great proven starting points for any hobbyist building just about any type of temperate or tropical vivarium. Even if your exact terrarium isn't listed, finding one in a similar size can help give you a good place to start.
 
Vivarium Lighting Solution Chart
Click any of the products above to visit the item's page on our web store
 
Working With An Inhabitant That Requires UVB?
If the inhabitant(s) you are housing require UVB lighting to synthesize vitamin D, you can replace one (or more) of the CFL bulbs over your enclosure with a UVB-Producing Compact Fluorescent bulb of similar wattage. If you'll be replacing Jungle Dawn LEDs, the 9W LED would be roughly equivalent to a 13W CFL, and the 11W & 13W Jungle Dawn LEDs would be roughly equivalent to the 23-26W CFLs(in terms of light output). Due to the different materials used for ultraviolet output, all UVB bulbs are slightly dimmer when compared most "standard" CFLs of similar wattage. (Including our plant-growth CFLs!) That being said, they are technically full spectrum bulbs that will perform well for a vivarium in terms of accurate color representation & plant growth. Use whichever UVB rating is best suited to your specific species, as your inhabitant's health should come first and foremost.
 
NEHERP Note
  UVB rays do not penetrate glass lids! Always position ultraviolet bulbs over screen portions of a vivarium to ensure UVB can reach your inhabitant!  
This doesn't matter for non-UVB producing bulbs, so unless your inhabitant requires UVB: No worries! (Rememeber: Plants don't need UVB!)
 
 
Choosing the Right Fixture
Choosing the best fixture comes down to what type of bulb you are using. If you are using a CFL, you want to get a fixture that will reflect as much light as possible, while allowing heat to escape the fixture to keep temperatures down within the vivarium. Good fixture choices for screw-in lights include Exo Terra Compact Tops, Zoo Med Terrarium Hoods, Zoo Med Deep Domes, Exo Terra Polished Domes, and standard "clamp lamps". Higher-wattage compact fluorescent bulbs can be too long to sit flush in a standard clamp lamp, so be sure you choose a fixture that's deep enough if you'll be using a 23W+ CFL. For Jungle Dawn LEDs, any horizontally oriented screw-in type fixture will work because the bulbs are unidirectional, and require no reflector.
 
Tube style bulbs (T12, T8, T5) require more expensive housings than standard screw-in bulbs. You don't want to spend your entire lighting budget for just a fixture, but cheap non-reflective fixtures aren't a good choice either. As much light as possible must be reflected downward into your vivarium for the best results. A white reflector won't reflect as much as a mirror-polished one, and cheap housings with black reflectors should be avoided. Ballast types are important when choosing a fixture for a tube fluorescent! Inexpensive magnetic ballasts don't last as long, produce more heat, and can create an annoying hum or buzz sound. Electric ballasts last longer, produce less heat, and don't hum (as badly). Most fixtures are labeled with a ballast type, so keep that in mind when choosing which is best for you.
 
Timing Your Light Cycle
Most plants do best with lighting set to about 12 hours on, and 12 hours off. This can be done with a simple outlet timer. A digital model isn't required for this application, although it's nice not needing to reset timers after a power loss! During hot summer months, you can set the day/night cycle to as little as 10 hours on and 14 hours off to conserve energy & reduce heat. Try not to change the cycle too often, as it can stress the enclosure's inhabitants. (If there are any) When using a timer, please keep an eye on your amp load! Overloading a cheap 5 amp timer (commonly sold at hardware stores & box stores) is a fire hazard. If you are timing only a handful of bulbs, it's usually nothing to be concerned about. If you are timing a breeding room, or a series of higher wattage bulbs, be sure not to exceed your timer's specs! All brands of timer in every store in the USA are required to list amperage ratings, so check before you buy. (All of our timers are rated for 15 amps (1875W!) minimum, which is the same as the average household circuit.)
 
Tips, Tricks, and Other Useful Info
 
 Vivarium plants do not need UVB. The only time UVB lighting is necessary in a vivarium is if you are housing an animal that would benefit from it.
 
 Something that's often overlooked: The vast majority of terrarium plants don't grow in direct sunlight in their natural setting, so you don't need tons of light for them to thrive. We see a lot of people drowning vivariums in light, which is unnatural, and not the best growth conditions for many vivarium plants. Certain plants (most commonly epiphytes, in a tropical vivarium) need a lot of light to produce lots of color as it would in nature. You can do this most efficiently by mounting the plants higher in the terrarium; closer to the light source. (Remember the inverse squared law!)
 
 Lighting doesn't need to cost a fortune. Spending a ton of money on a fixture or light bulb doesn't guarantee anything besides a lighter wallet. If you have questions about lighting, ask someone who's done it before. More often than not, you can illuminate a vivarium on a fairly tight budget. Be wary of anyone suggesting T5HO or LED bulbs as an "absolute bare minimum", as the advice is often incorrect. Both are great, but try and understand the pros & cons listed above before making a purchase. Everyone's goals are different, and there are a bunch of easy ways to get the job done. Personal preference plays a big part, here!
 
 If you are concerned with heat in your vivarium and aren't sure whether to use LEDs or CFLs, test it 1'st! Most CFLs of the same wattage operate at roughly the same physical temperature, so if you have any CFLs lying around your home, you can test them in your vivarium before spending the money plant growth bulbs. If the enclosure gets too hot, you'd better stick with LEDs. If it's cool enough, you can save a little money and stick with CFLs.
 
 "What about metal halide & high pressure sodium bulbs?" Both can produce large amounts of light, but also produce extreme amounts of heat. Maybe if you are building a massive (walk-in size) vivarium, but otherwise these aren't a good choice for most average sized terrarium builds.
 
 Positioning a fan to blow over the lights can cool even very warm methods of lighting. Keeping air moving over hotter bulbs can go a long way for keeping things cool. Even a small "desktop fan" can drop temperatures in a vivarium significantly. We added 4 recirculation fans in our old (500sq/ft) breeding room that primarily used T8 and CFL lighting, and the average top portion of cage temperatures dropped a whopping 7 degrees! (Measured with an infrared thermometer)
 
 Temperatures can range 5-7+ degrees from top to bottom on taller enclosures! Don't just measure the lowest part, as it'll always be the coolest. Infrared thermometers go a long way when it comes to figuring out the exact temperature between different parts of your vivarium.
 
 Building a rack system? We suggest sticking to roughly 48" wide shelves, if possible. Both T5HO & T8 lighting in the 48" length are the best bang for your buck, compared to other tube fixture lengths. (The 4 foot length is by far the most popular size, so manufacturers are able to price them accordingly.)
 
Get everything you need to build an awesome vivarium right here at NEHERP, with the best selection & lowest vivarium supply prices anywhere!
 
Substrate Base Kits | Vivarium Lighting Kits | Plant Packs | Enclosures | Wood Decor | Wood Accents | Natural Vines | Microfauna | Misting Supplies
Thanks very much for choosing us as your vivarium supply & info source!
If you have any questions at all, don't hesitate to ask us.  We're always happy to help!