Melissa Kaplan's
Herp Care Collection
Last updated January 1, 2014

Reptile Lighting

You may not be getting what you think you are buying...

©1996 Melissa Kaplan


Any incandescent bulb is fine for heat (for night time, you want dark light, such as the Nocturnal light by Energy Savers Unlimited or a ceramic heating element). The technology (tungsten filament vs. the gases and coatings used in fluorescents) doesn't produce UVB, and only marginal UVA (which is the wavelengths in between UVB and visible light).

"Full spectrum" is a term now used rather loosely. It can mean "produces UVB, UVA, visible light and infrared [the wavelengths longer than those in the spectrum we can see (visible light) but the reality is that manufacturers of incandescents are calling their bulbs 'full spectrum' to lull people into thinking they are getting UVB (and thus buying their product) when they are not. UVB lighting manufacturers are calling their UVB-producing fluorescents "full spectrum" because they produce the full spectrum of visible light (Gehrmann, Reptile Lighting: a current perspective, 1997).

Incandescents are fine to use alone for heat for herps that don't require UVB, such as snakes; nocturnal lizards; diurnal lizards from more northerly or temperate climes who do well with minimal UVB obtained from occasional exposure to natural sun when handled outside the enclosure; some chelonians, such as mud-dwelling common musk turtles [Sternotherus odoratus]; and amphibians. UVB-producing fluorescents emitting sufficient UVB for the species must be used in conjunction with incandescent and other heat sources for all other diurnal lizards and all chelonians who require UVB exposure.

What's the difference between a WIDE Spectrum and a FULL Spectrum light?
Ahhhh....welcome to the Madison Avenue and the non-regulated pet product industry where accuracy never gets in the way of making product claims! Because there are no truth-in-advertising regulations covering pet products, manufacturers can be as misleading as they like. Like the 'iguana approved' reptile bark and litter products: keep your iguana on them and your iguana will be facing impactions, surgery, even death. Manufacturers and pet stores don't care: by the time that happens, they've already made their money off you.

It used to be that 'full spectrum' lighting meant lights which produced both ultraviolet B, ultraviolet A and the full visible spectrum as well infrared heat. Once incandescent manufacturers figured out that people were being told to look for 'full spectrum' lighting, they started to market their wide spectrum incandescent lights (producing some, but not all of the visible wavelengths and no ultraviolet wavelengths) with the words 'full spectrum' in the ads and on packaging. Thus people who buy Chromalux, NeoWhite and Reptile incandescent lights think, incorrectly, that they are providing UVB and UVA as well as the full visible wavelengths and heat to their reptiles. In fact, incandescents are just producing, if they are putting out bright white light, only the visible spectrum; some types of lights (such as the Chromalux) are not necessarily even producing the full visible spectrum, being corrected to increase or reduce certain parts of the visible spectrum.

Fluorescent light manufacturers weren't slow to get on this bandwagon, either - unfortunately, not all fluorescents produce UVB wavelengths, either... They are shielded to reduce the dangers to humans (and their fabrics) or permit so little UVB to pass through that it isn't sufficient to promote adequate previtamin D formation, resulting in a reptile with metabolic bone disease.

When is 6% more than 10%?
The problems with truth in advertising goes beyond the misleading use of the term "full-spectrum". When it comes to UVB-producing fluorescents, the percentages given are not particularly useful as the manufacturers rarely tell you what that is a percentage of. If you have a light producing, for example, 20% of its total wavelengths in the UV range, and of that 10% is in the needed UVB range, while another light produces 40% of its wavelengths in the UV range, with 6 percent of that in the UVB needed range, the product with 6% of the 40% is going to produce more UVB in the needed UVB range than the other product. The product with "10%" on the package may look like the better light than the one that says "6%", but it isn't if that "10%" isn't providing enough UVB for your reptile.

Quick Index to Tables
The following tables are based on tables by lighting specialist William H. Gehrmann, in Evaluation of Artificial Lighting (in Reptile Medicine and Surgery, 1996, edited by Douglas Mader DVM):

1. Table of UV and Visible Light
2. Table of UV Transmission through Typical Caging Materials
3. Fluorescents Producing UVB


Note: Wavelengths responsible for conversion of 7-dehydrocholesterol to cholecalciferol: 280-315nm




UVB 290-320 nm, UVA 320-400 NM, Visible 400-700 NM, Infrared >700 NM

Incandescents (frosted, reflector floods, spots, halogen lamps

UVA 320-400 NM (low levels), Visible 400-700 NM, Infrared >700 NM


Chroma 50, Colortone 50, Design50, Cool White, Warm White

Visible 400-700 NM
UVB 280-320 NM (low levels), UVA 320-400 NM (low levels)

Plant lights

Emphasize red and blue spectrums within Visible 400-700 NM

Blacklights (BL)

UVB 290-320 NM (low levels similar to Vita-Lite), UVA 320-400 NM

Blacklight Blue (BLB)

Same as BL but with less blue light emitted; reported harmful to eyes

Sun lamps, Germicidal Lamps, Phototherapy lamps

High levels of UVB causes skin cancer, cataracts, etc.

Other UV Sources:

High Intensity Discharge Mercury, Metal Halide

Visible 400-700 NM, Infrared >700 NM; UVA and UVB are shielded due to extensive damage to skin and eyes caused by such high intensity

Mercury vapor combo heat/UV product

Extremely high output of UVA and UVB posing health hazards to humans and reptiles in typical home setting



















Window glass, single thick



Acrylite GP acrylic, 0.635 cm



Acrylite OP-4 acrylic, .318 cm



UV-T Plexiglas, .635 cm



Cellulose triacetate



Galvanized mesh, .318 cm (0.13")



Galvanized mesh 1.270 cm (0.5")



3. So, what lights do produce UVB?
(Please be sure to read the comments on the indicated lights.) The following are in alphabetical order only; those underlined are your best choices:

  • Blacklights( BL Blacklights; not blue or black incandescent light bulbs*)

  • DayCycle (TetraTerrafaun)
  • Iguana Light and Reptile Light (Zoo Med)ƒ
  • Lumichrome 1XX Full Spectrum Fluorescent Plus
  • Repti-Glo, Sun-Glo (Hagen)
  • Repti-Sun (Zoo Med; replaced by their newer Iguana and Reptile Lights)ƒ
  • Reptile Daylight (Fluorescent; by ESU)#
  • Reptile-D Light (National Biological)+
  • Ott Light (available in Europe - Vita-Lite makes a comparable product)
  • Vita-Lite (Fluorescent tubes, not compacts; made by Durotest)

# Iguana owners have been reporting onset of MBD within ~6 months of using the early version of ESU's UVB tube despite proper diet and vitamin and calcium supplementation, and who had not before exhibited any signs of metabolic bone disease. In the past couple of years, they have come out with a higher output ("7%") light; I have not heard of any problems reported with the new "7%" tube.

* BLB lights have been reported to cause eye diseases and should be avoided.

+ Lights producing more than 5% UVB carry warnings on them relating to damage to human eyes. I've been unable to track down my reference on this (supposedly from OSHA regs, but folks I've talked to at OSHA can't find it) and the more I dig into UV lighting "specs" the more murk I find. According to an "independent" analysis Zoo Med had done, the Reptile-D light does not in fact produce 5% UVB, it produces slightly less than the Zoo Med 5.0 light (4.84 vs 5.02). What is interesting is Zoo Med's fact sheet that states "It is Zoo Med's opinion that UVB bulbs that exceed 5% total energy output should not be sold [to] the general public (emphasis theirs)." So, on the one hand, they "prove" that their lights are better than the Reptile-D light because they produce more UVB than the Reptile-D, but at the same time theirs exceeds (true, by a very slight amount) their own safety recommendations. They also go on to say that, "just as you would not stare at the sun, never stare for any length of time directly within 12" of a UVB bulb." To date, no pet manufacturer has made goggles for lizards to protect their eyes from staring at high UV output sources...which is why UV-tubes made for the tanning industry should never be used.

ƒ Zoo Med periodically changes the names and packaging on their lights. Their "Iguana" light is identical to their "Reptile" light, other than the packaging. Some pet stores sell the Iguana or the Reptile tubes for more than the other, even though Zoo Med's wholesale price is the same for the two products. The Reptile and Iguana tubes are interchangeable and can be used for any species that needs such a product.

Observations in studies on vitamin D3 indicate that very high output (VHO) bulbs may cause a form metabolic bone disease, the very condition one is trying to avoid through the use of UVB lighting, by causing a sort of overdose of systemic D3. If you are going to use these high output bulbs, including mercury vapor products such as ActiveUV and Zoo Med's new PowerSUN, have your reptile's blood and eyes checked regularly. Remember that, in the wild, iguanas aren't in direct sunlight all day long, but thermoregulate by moving frequently into the shade. So, just because a UVB-producing fluorescent doesn't provide the same amount of UVB as the sun does at the equator or elsewhere in the iguana range, the iguanas don't need the amount that pours down on the forests and ground in the tropics. Given that they do quite well in captivity with properly positioned and annually replaced Zoo Med's reptile or iguana, and Durotest's Vita-Lite tubes, fluorescents, the fact that these products produce less than the sun at the equator is a moot point. It simply doesn't matter in terms of your being able to provide adequate UVB in captivity.

I also suggest you read Anne Marsden's new article which summarizes the research into UVB and D3, Sunlight and Reptile UVB Tubes: The Value of UVB Exposure.

Related Articles

Neodymium Lights 

Musings on UV and D3...

Comparison of the UV-B [Lights] With Natural Sunlight

UV Lighting - General Information

ZooMeds Claims (note that the charts are too small to accurately read how much UVB produced at each nm)

UV-lamps for terrariums: Their spectral characteristics and efficiency in promoting vitamin D3 synthesis by UVB irradiation

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