Types of lighting

There are many lights on the market today, many aimed specifically for reptile keeping. Not all however are suitable for Vitamin D3 production.

Flourescent Lights

Strip lights contain low pressure mercury vapour which when iodized (electric current passed through it) emits UV light. This energy (UV light) is then absorbed by a thin coating of white phosphor on the inside of the bulb. The white phosphor uses the energy from the UV light to emit visible light (it fluoresces). Some energy is wasted as heat but most is changed to visible light.
The colour of light emitted (cool white, soft tone, Beauty Lights etc) depends on the
chemicals mixed in with the phosphor powder. Normal glass blocks 95% of UVB and 30% of UVA therefore any UVB and a noticeable amount of UVA not changed to heat and light by the phosphor coating is effectively absorbed by the glass casing.
Examples of this type of bulb are cool white office lights, kitchen lights and aquarium lights.
These types of bulb do not produce sufficient UVB however they are useful when used in conjunction with a UVB producing light to increase the amount of light in vertical enclosure.

Specialist Reptile UV Flourescent Lights

The sleeves of these bulbs are made of quartz instead of glass. Quartz allows UVA and UVB to pass through freely. In addition as the aim is to produce UV light the phosphor coating is thinner. Consequently as less of the UV created by these bulbs is absorbed by the phosphor coating, UV producing fluorescents that produce a decent amount of UVB (1-5%) aren't very bright (and have a lower CRI) and conversely bright UVB producing fluorescents do not produce much UV.
As well as UV light, iodized Mercury Vapour also emits some green and blue visible light. That is why UV lights look grey/violet to the eye.

It is advisable therefore, for sun loving species, when using a UVB producing fluorescent, to also use a white light emitting source as well - this will give your diurnal reptiles both the UV and the bright light they need.

In addition always maximise the amount of light reaching your reptile by using a reflector.

The Chameleon Information Network recommend using two Reptile UV producing flourescent bulbs in each enclosure. We have tried one UVB, one UVB and a 2.0 UV, and one UVB and a normal flourescent and have not noticed any adverse effects with any of those combinations. We would normally only use one UVB bulb in a horizontal shaped enclosure where the animal is never far from the bulb or when overheating can be a problem. In vertical enclosures two bulbs are better.

Full Spectrum Light

This is a common term used for Incandescent (tungsten) Reptile Basking
Lamps and Plant Lamps. This is misleading in that only visible light and a very small amount of UVA is produced. Basic tungsten bulbs do not produces UVB.
The term full visible light spectrum would be more accurate.

Several Reptile basking lamps available are covered in "rare earth elements". These are simply normal household bulbs coated with an element to remove the yellow light therefore slightly altering the way the environment is perceived (usually things seem slightly brighter).

It is far better and cheaper to use a household incandescent in conjunction with a UVB-producing fluorescent. Full visible spectrum will be produced as well as UVA and UVB.

This type of bulb includes Reptile basking lamps, household bulbs, reflector bulbs, plant gro-lux bulbs and Reptile "day-light" bulbs.
This type of bulb does not produce UVB

Halogen Lights

Tungsten halogen lamps are increasingly being used because they are a small and highly efficient light source. Halogen gas is used to capture vaporised tungsten atoms and replace them on the filament thus allowing the filament to run hotter and longer than conventional tungsten bulbs. Because of the higher operating temperature significantly more amounts of ultraviolet (UVA) as well as visible light is produced. To maintain operating efficiency the bulb wall must be hot (over 260'C), so it is made of quartz which withstands the heat better than glass, but absorbs less UVA. A significant portion of energy generated is within the UVA wavelength.

The Health and Safety Executive in the UK provide the following advice on the use of halogen lights in the work place:
"It is generally recommended that all tungsten halogen lamps should either be fitted with an appropriate UVR filter, or a bulb with a glass outer element. In particular, the use of unfiltered desktop lamps should be discouraged if they are used for more than 2 hours per day and are sited within 0.6m of the user. If a lamp is fitted with a double-walled bulb, but the outer wall is broken, it should not be used.
UVR exposure caused by some desktop tungsten halogen lamps can be comparable in some instances with levels of solar UVR in terms of its erythemal (sun burn) and potential carcinogenic (cancer causing) effects."

Compare the 2 hour period and 0.6m minimum distance cited with a typical Chameleon set up with a photo-period of 12 hours. This would increase the exposure dramatically. Clearly unfiltered light could produce a serious health risk. In addition consider that the filters often used only block light below 360nm. The UVA range is from 400nm to 320nm and therefore a significant range of UVA is still allowed through.

We do use small filtered halogen bulbs to create a basking spot for Stump Tailed Chameleons and have bred them frequently without any adverse effects. Halogens can produce a small, fairly hot basking area without significantly effecting the temperature in the rest of the vivarium. So are useful in smaller vivariums to allow the animal to thermo-regulate.
It should be noted though, that these vivariums are well planted with many hiding places and a layer of dead leaves to provide further shelter.

These lights must not be used without a UV filter.

Mercury Vapour Lamps
(eg Powersun and UV Heat)

When first released these were going to change the way we keep chameleons. This is true to some extent because they provide UVB for a much greater distance than the traditional flourescents. This meant a "free range" set up could be provided with sufficient UVB covering a greater area and heat, all from one bulb.

The problem with these bulbs is the same reason as the benefits. They are very powerful. In reality many chameleons do not bask for huge amounts of time. Possible exceptions are chameleons that come from areas, which are devoid of vegetation at certain times of the year. Examples being Veileds, Oustalet's and Verrucosus.

In summary they can be a good lamp if used in the right circumstances (large enclosures or free range) and with the right species of chameleon.

Note of caution
Several keepers have noticed reduced fertility and deterioration in the general health of Panther Chameleons kept under high powered (100w plus) mercury vapour bulbs. It has not been proved that the bulb is to blame but the animals in question improved when the lighting was replaced with Zoomed 5.0 tubes. For this reason we suggest very careful monitoring when using these bulbs.


Additional Lighting Characteristics



CRI or the Colour Rendering Index is used to compare the colour of an object viewed under artificial light compared to its colour when viewed under natural sunlight at noon. At noon the CRI is 100. The closer to 100 the CRI the more natural objects look.

People who suffer from depression throughout the winter but are fine throughout the summer are responding to the change in the CRI. The higher the CRI the better things look to us and to our reptiles.


This is the colour temperature (ie warmth or coolness).
When metal is heated, the colour of light it emits will change. This colour begins at red then changes to orange, yellow, white and then blue-white and finally blue. The temperature of the metal in Kelvin is used to describe the colour. Obviously the lower the more red and higher blue.
At sun rise the sun is approx 1,800 Kelvin (red/orange). This increases as it rises and changes from red to yellow to white at over 5,000 Kelvin at noon.
Preferred Kelvin for reptile lighting is from 5,000 to 5,500.


Measures the intensity of light leaving the light source.


Measures the amount of light actually reaching a given point. The target distance from the source as well as the intensity of the source effects this measurement.
100w, 60w, 40w and 25w household bulbs have similar lumens (intensity), but different lux. Consequently changing the wattage of a bulb used to create a basking spot directly effects the light and heat at the basking spot.
When creating a basking spot the aim is to create a bright area as well as a hot area as reptiles associate bright light with heat. If a dimmer stat is used with for example, a 100w bulb the bulb may only be burning very slightly for the area beneath it to reach the required temperature and consequently would produce very little light. It would also gradually warm up the rest of the enclosure resulting in a reduction of the thermal gradient therefore effecting the animals ability to thermo-regulate properly.
A better option would be to use a lower wattage bulb that needs burn brightly all the time to achieve the required temperature which consequently would also create the desired bright spot as well.

What the numbers on Reptile Lamps mean

Numbers, such as 5% or 10%, or in decimal form,8.0, 5.0 or 2.0, refer to the percentage of UVB light emitted within the total amount of light energy produced. i.e. 10% means 10% of all light emitted by that bulb is in that given range.

These numbers can not be used to determine which bulbs produce most UV for the reptile unless the total amount of light emitted is also given.

Length of UV Production in bulbs

Over time the amount of UV light emitted drops significantly although visible light is still produced. Tube manufacturers recommended that you replace the tube at least every 12 months (most suggest between 6 - 12 months). Usually after 12 months the tube is no different from a standard fluorescent tube in terms of UV output. A good way to ensure that you change your bulb regularly is to write the date it was first used on the end of the tube in a permanent marker. This way it doesn't matter if you move the tube, change setups or whatever, as you'll always know when it's time for a change.

A fresh UV tube is particularly important for rearing baby chameleons as the demand for calcium in their rapidly growing bodies is much greater then when they are adults.
We also suggest breeding females are provided with new lights more frequently than the manufacturers suggest.

Other lamps such as sunlamps have been recommended for a limited period each day. The problem with this setup is if the light is on a timer the chameleon may not be under the light when it switches on. Also this type of bulb would create an abnormal period of light intensity which could cause stress and stress related health problems.

Using less effective D3 lights, such as the purpose build reptile D3 flourescents, for standard photoperiods result in sufficient doses of UVB.

Look out for updated information regarding UV lights and ageing results here

Getting UVB to the required place

Once a UV bulb has been obtained the next problem is to ensure the beneficial wavelengths actually get to the Chameleon.

UVB from many specialist Reptile UV fluorescents do produce sufficient UVB. The big problem is getting UVB to the reptile as so many substances (including air) absorb UVB and a lot of UVA.

UVB will not travel through most types of glass. Only horticultural glass used in some greenhouses allow UVB to pass through.

Therefore placing a UV light outside a fishtank or glass vivarium is a complete waste of time and is dangerous to the chameleon (fish tanks should not be used to keep chameleons in anyway as they do not have sufficient ventilation, even with all mesh tops!)

Window glass also blocks UVB. Putting your Chameleon on a plant on the window sill (or conservatory) will not expose it to any UVB but does allow some UVA through which can have a beneficial effect on their mood (see earlier notes on UVA).
Please note that windowsills in direct sunlight can get very hot. Always ensure your Chameleon can move into a cooler area. Water should also be made available in suitable quantities (see WATER)

Most plastics filters UV light. Even mesh filters up to 30% of UVB.

Safety Note: We do not recommend the use of cages around the UV bulb or the basking lamp. We have found that if a Chameleon can reach the cage it is very likely to climb on it and often hang upside down from it, thus exposing its soft underbelly to excess UV and heat at too close a distance. This often results in burns that can be fatal. All of our UV bulbs and spot bulbs are situated in such a way that the chameleon can not reach them so the need for protective cages is eliminated.


There is no substitute for the real thing. With the possible exceptions of the forest floor dwelling chameleons such as the Rhampholeons and Brookesia all Chameleons fair better when exposed to natural sunlight.

Whenever possible regular exposure to natural unfiltered sunlight is highly recommended.
A few pointers below should however be born in mind:

The chameleon must be able to retreat from the direct sunlight to somewhere cooler. Natural plants work well in this respect as they not only provide shade but the humidity produced from the leaves also cools the air immediately around them.

Drinking water should be provided at all times (we have observed fussy drinkers drink huge amounts from drippers in outside enclosures when they would take little interest indoors). Misters (which can now be bought cheeply from garden centres) should be used in hot weather to prevent the chameleon overheating. The mister should only cover part of the enclosure so the chameleon can move in and out of the mist when it wants to.

Chameleons should be housed in a suitable enclosure to prevent escape or attack by predators (this includes mesh small enough to stop bees and wasps entering if your garden has many). Glass should not be used on outside enclosures.

Extremes of temperature are to be avoided.

Screen cages designed so that they can be taken outside are particularly suitable. If the chameleon can be taken outside in its own enclosure on suitable days this helps reduce stress associated with the chameleon getting used to his new surroundings.

Current lighting research

We have recently invested in a UVB testing meter. The aim is to test the UV lights curently available and how best to set them up to optimize the UVB available to our chameleons.

We are testing how reflectors and various meshes effect the amount of UVB reaching the target. Over the coming months we will also be testing how the resultant UVB drops off with age.

As this is an ongoing project we will be posting links to pdf files with our current results. Eventually they will be added in full to the website but this method allows us to update our findings quickly and regularly until finalized.

  • General Introduction to the testing and the measurements we are taking.
  • Review of Zoomed 5.0 Reptisun and Repti-glo 5.0 and 8.0 Lamps
  • Table to work out the UVB reaching your basking spot


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