Vivarium Lighting 101
Everything you need to know about illuminating a vivarium!
This article is part of our informative vivarium building series of articles.
The "10 Commandments" Of Vivarium Building • Vivarium Construction 101 • Vivarium Construction 102
Common Types Of Vivarium Lighting: Jungle Dawn LED, "Corn" LED, Compact Fluorescent, T5, T8, T12
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 the basics 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.
"Will the light be bright enough?"
Lumens are the unit of measurement of light intensity or brightness emitted by a source. Most bulbs are rated for lumen output (luminous emittance), which is the indicator most often seen when determining "how bright" a bulb will appear to the eye. The term for metering how much light is incident on a surface is called illuminance. (lumens per square meter, or lux for short) Lumens add/stack, meaning if you have two 1000 lumen rated bulbs in a fixture, the total luminous emittance will be approximately 2000 lumens. Lumen ratings of a bulb are very important in vivarium building because this will determine how visibly bright the enclosure will be to the human eye. Lumens help us determine whether or not a display will look sufficiently bright to human eyes using a specific light source.
Kelvin (Color Temperature)
"Will the light look right & grow plants properly?"
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, so if you use two 5000K bulbs, the Kelvin rating remains 5000K. Kelvin helps us to get a rough idea whether or not a plant will 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. If you have to choose one or the other, we personally prefer bulbs around the 5000-5500K range for the warmer appearance. 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 use for photosynthesis. This unit of measurement is frequently used in both agriculture and the aquarium hobby, since reefs and some underwater plants require significantly more photosynthetic active radiation 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. Having said that, 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.
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 85+ 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.
Inverse Square Law
"Is my vivarium too tall for this light source?"
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. The inverse square law is why a vivarium's height is so critical in determining a vivarium light source.
For example, a 24" tall vivarium would require a light source that's roughly four times as bright as a 12" tall vivarium, to receive the same measureable illuminance at the bottom. Understanding the inverse square law is critical when building vivariums over 24" tall, since in our experience, you'll end up needing some extremely bright lights to fully illuminate such a deep a vivarium. If your vivarium will be over the 24" mark, you'll want to consider T5HO, unidirectional spot LED lighting, or other fluorescent lighting with a fixture that'll concentrate as much light downward as possible. (Higher wattage 32W CFLs with deep dome fixtures fit the bill nicely!) Selecting a light fixture with a good reflector is critical, if you'll be 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. For vivariums 24" and under, we have a chart near the bottom of the article to help you decide which bulbs & fixtures would fit your build specifically.
Available Bulb Types
There are a few basic types of lighting commonly used in vivarium building today, with the most popular being fluorescent (T12, T8, T5HO, CFL, PC), with newer vivarium-specific LED technology quickly closing the gap. Below is a breakdown of each type, with advantages & disadvantages explained in detail.
Compact Fluorescent Bulbs
Compact Fluorescent Bulb With Integrated Ballast (most common)
Probably the most-used type of vivarium lighting today. Compact fluorescent bulbs are available in a very wide range of shapes, sizes, wattages, color temps and fit the most inexpensive (and common) light housings. These bulbs are available with or without an integrated ballast. Without an integrated ballast, the bulbs are slightly more efficient, but significantly more expensive. In our opinion the cost outweighs the benefit of using non-integrated ballast bulbs. 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.*
• The most inexpensive way to light a vivarium
• Widely available both online and in your local hardware store
• Available in a wide range of lumen output (these are the highest lumen per dollar option)
• Available in a wide range of color temperature
• Can be used in the least expensive housings
• Higher wattage bulbs produce a fair amount of heat
• Unless nice housings are used, they aren't an extremely efficient bulb
• Certain higher wattage bulbs won't fit in some standard housings (They can be too long)
Standard Fluorescent Bulbs
T5 Bulbs = Extremely Efficient T8 Bubs = Efficient T12 Bulbs = Not Very Efficient
There are three types of commonly used tube fluorescent bulbs. In order of most efficient to least efficient: T5, 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 the widest range 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. Generally speaking, size usually determines watts unless you are comparing a "HO" (high output) to standard bulbs of the same size & type. Standard "tube" fluorescent bulbs are most commonly used with larger enclosures, or with "rack style" breeding setups. The 48" widths of bulbs & fixtures are extremely common and very inexpensive. Smaller bulbs & fixtures are available, but are usually very expensive when compared to CFL or LED bulbs that could do the same (or better) job. 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 *
Vivarium Specific LED Bulbs
LED bulbs are improving every day, and becoming less and less expensive as time goes on. In 2008 for example, most LED bulbs were expensive and fairly dim. Nowadays technology is improving and they are quickly becoming the most efficient type of lighting used today. Unfortunately prices are still fairly high compared to fluorescents, but the big advantages are 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. Specially designed, vivarium-specific "Jungle Dawn LED" bulbs have become readily available thanks to LED Designer & herp enthusiast Todd Goode. His bulbs have a combo of two different color temperatures (which is ideal), high quality LED diodes, and are inexpensive considering their performance. If heat is a concern, Todd's Jungle Dawn LED bulbs are an excellent alternative to fluorescents.
Advantages of Vivarium-Specific LED Bulbs:
• The most energy efficient bulbs
• Less expensive than T5HO
• Excellent combo of color temperature
• Can be used in the least expensive housings
• Unidirectional for excellent light penetration
• Extremely long bulb / diode life
• Accurate color representation within a vivarium
Disadvantages of Vivarium-Specific LED Bulbs:
• Fairly Expensive Compared To CFL
• Not quite as bright as T5HO lighting
NEHERP Note: We are not describing Chinese-made cheap 'Ebay corn-style bulbs'. In our testing of three different types of those bulbs, NONE produced significantly less heat than a low-wattage CFL. One type (we tested 3 individual bulbs) literally melted in the Zoo Med housing (See picture) and became a fire hazard. We suggest you save yourself a kick in the wallet and skip the Chinese-made bulbs. If we thought there was a good, super discount-priced, LED vivarium bulb, we'd stock them!
Overall Lumens 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 75-100+ lumens per watt **
* Non-scientific information compiled & averaged from a variety of manufacturers & light-testing sources and is for informative use only. HO Bulbs use more energy, and produce more light.
** The lumens per watt range of LED bulbs is improving towards 100LPW rapidly as technology gets better. Generally speaking, the better the LED, the more efficient it is at producing light.
How To Select A Vivarium Light Source - "The Hard Way"
Technically the most accurate method to select a more complex lighting source.
There are two schools of thought in determining which type of light bulb to choose. One method would be to balance CRI, PAR, Kelvin, and Lumen output to determine exactly which bulb will work best for your vivarium. The inverse square law should also kept in mind for your specific enclosure size. This involves keeping an eye on CRI & Kelvin to ensure things appear accurate to the eye, referencing PAR to ensure your are pushing as much photosynthetic efficiency as possible, and finally checking to be sure the light sources have a high enough lumen rating to ensure the vivarium will be visibly bright enough to the human eye. This requires a fair grasp on the above concepts, and is not generally the best way for a newer enthusiast to select a light source.
How To Select A Vivarium Light Source - "The Easy Way"
A simple, accurate, and proven way to figure it out 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 most common, easiest, and most reliable way to choose a vivarium light source for years, and it's the method most hobbyists today use when choosing a light source. For most common sized vivariums, there's no reason to blow your hard-earned money on super-high-output advanced lighting systems designed for aquariums or agricultural growing operations, when inexpensive fluorescent or Jungle Dawn LED bulbs will do an excellent job at a quarter (or less) the cost.
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 human eye.
(A naturally accurate light source is critical to the overall appearance of a vivarium. This is as simple as using a full spectrum bulb with a color temperature similar to daylight (5000-6500K).)
Goal #2: Light should penetrate to the base of the enclosure for a nice looking, well illuminated display that'll support flora life top to bottom.
(No point in building something if you can't see half of it! Keep the inverse square law in mind here, and ensure your light source has a high enough lumen rating.)
Goal #3: Ensure the vivarium's lighting will sufficiently grow terrarium plants long term.
(Most bulbs in the correct color temperature range will grow plants in the vivarium setting flawlessly. PAR ratings can also be used for determining photosynthetic efficiency, if available.)
Goal #4: Don't go broke in the process.
(There's no good reason lighting needs to cost a fortune. Even super-inefficient T12 fluorescent lights can grow most vivarium plants effortlessly, so long as it's done right!)
With all the lighting information in mind, we created the above chart to help make choosing a light source as easy as possible for common vivarium sizes. Although every vivarium's requirements can vary, the above options are a great starting point for any hobbyist building just about any type of temperate or tropical vivarium.
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 of the CFL bulbs over your enclosure with an Exo Terra Repti Glo Compact Fluorescent bulb of similar wattage. If you'll be replacing Jungle Dawn LEDs, the 9W LED would be roughly equivalent to a 13W Repti Glo, and the 11W & 13W Jungle Dawn LEDs would be roughly equivalent to the 26W Repti Glo bulbs. These Exo Terra bulbs are slightly dimmer than the plant growth CFLs & Jungle Dawn LEDs they'd be replacing, but they are technically full spectrum bulbs that will perform well for your vivarium otherwise. Always use whichever UVB rating is best suited to your specific species, as your inhabitants health should come first and foremost in every decision made for your vivarium.
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 fluorescents 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 uni-directional, 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 heat, and can produce 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
This is pretty simple. 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. (You don't need a digital one 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. (Assuming 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. (Our marineland timers are rated for 15 amps (1875W!), 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 extreme 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.)
If you have any questions at all we're always happy to help! Email us at email@example.com
Back to Vivarium Care
Back to Care & Media
To The Supply Menu
To The Main Store Menu