One of the most controversial topics when it comes to keeping crested geckos is that of UV lighting.
In this guide we’ll try to tease apart fact from fiction, discussing the pros and cons of ultraviolet lighting for cresties, and look at some of the best bulbs on the market to help you select the most appropriate product in what can a complicated and muddling area of reptile care.
Why Do Reptile Keepers Use UV Lights?
Bones are made from a number of different nutrients, but possibly the most important of these is calcium. Sadly it isn’t enough to just provide calcium in the diet – vitamin D is also required for your body to be able to use calcium to create a strong skeleton. Think of them as mutually crucial – you’ll need both elements for strong, healthy bones.
Vitamin D is created in the skin through a complex process that is triggered by ultraviolet light. Put simply, therefore, UV light helps the body to create vitamin D which, in turn, helps to body to absorb calcium and so create strong bones.
Historically, early reptile keepers were plagued by problems caused by a lack of vitamin D. Back in the 1980’s and early 1990’s numerous green iguanas and other popular lizards started to suffer from Metabolic Bone Disease (MBD).
Their skeletons weakened, and fractures became more common. Eventually some pet lizards became paralyzed, both through their weakened skeleton and because calcium also plays a crucial role in the process of muscle contraction.
With suitable calcium supplementation and the introduction of modern UV lights these problems went away, but it does go to demonstrate the importance of these minerals to many species of captive reptile.
UV Lights Vs. Dietary Vitamin D Supplementation
UV lights aren’t the only option for pet reptiles. Another possible solution is to provide vitamin D in supplement form. Indeed, here in the UK where I live the government recommends that all Brits take a vitamin D supplement during the winter months because the sun isn’t strong enough for our skin to generate sufficient vitamin D.
The same routine of vitamin D supplementation can be applied to reptiles, and a range of high quality vitamin D supplements are available for feeding to livefood, or dusting them with, or adding to water.
So why not just do away with the expense and hassle of UV lights altogether, and instead just focus on supplementation? Well here there are potential risks too. For one, we’re still not totally sure how much vitamin D many lizards – including crested geckos – actually need. Secondly, even if you dust your feeder insects you can’t be certain how much of the mineral dust your lizard is actually eating.
Vitamins can be divided into two categories – water-soluble vitamins and fat-soluble vitamins. Water soluble vitamins pass through your body and any excess is rapidly excreted. These vitamins need to be consumed regularly if you are to avoid a deficiency. On the other hand, it is difficult to take too much because they just flush through your body so quickly.
Vitamin D is the other type – it is fat soluble. This means that your crested gecko can store it in their body. Give them too much and there is a risk that toxicity can appear. This, in turn, can have all manner of side effects including odd skeleton growth, weakness and kidney problems.
In other words, giving too much vitamin D can be just as bad as too little. All that while we don’t really know how much vitamin D a crested gecko really needs. Sounds risky? It can be.
This is one of the arguments raised by crested gecko keepers who believe that ultraviolet light is a good thing for their pets. A great thing about providing UV light is that your gecko can opt to expose themselves or not. They can therefore regulate their absorption of vitamin D rather than having vitamin D forced on them in supplement form.
Do Crested Geckos Need UV Lights?
As mentioned earlier on this article many crested geckos keepers disagree wildly about whether cresties need UV light.
On the plus side, reptile experts point out that providing UV light gives their cresties control over how much they are exposed to, and therefore to the level of vitamin D in their bodies. Look around at some forum threads on the topic and you’ll also find that many keepers have claimed that the provision of UV light has made their crested gecko more active and generally healthier-looking.
The cynics, on the other hand, point out that crested geckos are nocturnal, so likely wouldn’t be exposed to much natural sunlight in the wild. Therefore, they argue, UV light is unnecessary and dietary supplement with vitamin D is perfectly acceptable.
It is worth pointing out that crested geckos kept without artificial UV light seem to live just as long, and don’t seem to suffer any unpleasant health condition when supplemented correctly.
At present, therefore, there really is no “right” or “wrong” answer. Everyone has their own opinion, and yours may be swayed by friends, or by the breeder or the pet store you bought your crested gecko from.
My own opinion – and it is just an opinion – is that the provision of UV light doesn’t seem to do any harm, and may actually offer some benefits. Therefore, due to the low cost of good quality UV lights these days I opt to provide some UV lighting to my crested geckos each day, but my bulbs are turned off at night to reflect a natural day/night photo-cycle.
Hopefully in this manner I have the best of both worlds; I see UV as an “insurance policy” on the health of my cresties – and a cheap one at that.
So, assuming you too have decided that you want to provide UV lighting to your crested gecko the obvious next question is what UV bulb is best…
Best UV Lights for Crested Geckos
Historically there have been two different styles of UV lights for reptile keepers. The first of these is the long strip light, as used in many larger reptile cages. For crested geckos, however, these aren’t the most suitable lights simply because they are so much larger than the average crestie cage.
A better alternative are the new breed of compact fluorescent UV lights. These look rather like a long light tube all coiled up into something roughly bulb shaped. These compact UV bulbs offer a lot of benefits to the crested gecko keeper. They’re cheap to buy, they’re small in size, they offer a high ultraviolet light output and they are easy to fit in most commonly-used crested gecko cages – such as the ever-popular Exo Terra glass vivariums.
The level of UV light experienced in different habitats varies. Consider, for example, the difference in the intensity of sunlight experienced in dry, desert areas versus the filtered light hitting the jungle floor. For this reason you will find a whole range of different UB bulbs for sale marketed as having a specific percentage of UVB light.
Generally for forest-dwelling and/or nocturnal species like the crested gecko you’ll want to focus your attention at the lower end of the scale. For cresties the 2% and 5% bulbs are generally recommended, with more powerful bulbs like the 10% UVB models generally best reserved for species like bearded dragons who come from much sunnier areas.
With these two decisions made let’s now look a little more closely at a few of the best UV lights for crested geckos that meet these specifications – a “compact” design ideal for a crestie cage offering between 2% and 5% UV light…
Zoo Med ReptiSun 5.0 UVB Mini Compact Fluorescent
At the same time, however, the ReptiSun also offers a reasonably high level of UVA. UVA is considered “visible” by reptiles, and there is some evidence that a bulb like this will encourage more natural behavior in captive reptiles. Some keepers claim that bulbs like the ReptiSun can encourage stronger feeding responses and may also be helpful if you try to breed your crested gecko in the future.
Lastly the Zoo Med ReptiSun 5.0 seem to have quite a long life, which isn’t always the case with other UV lights for reptiles, many of which die after a matter of weeks. All in all, therefore, the ReptiSun 5.0 is a good option for most crested gecko cages.
Exo Terra Repti-Glo 2.0 Compact Fluorescent Full Spectrum Terrarium Lamp
As the name suggests, the Repti-Glo 2.0 has a slightly lower UVB output than the Zoo Med ReptiSun discussed above. Indeed, Exo Terra market this particular bulb as ideal for nocturnal lizards like crested geckos.
This bulb has also been designed to offer suitable light to encourage plant growth. As a result, this can be a good bulb to use if you’re planning to plant up your crested gecko cage to resemble a jungle.
That said, a couple of concerns have been raised by users of this bulb. For one thing, the light that it produces is ridiculously bright – ideal for plant growth but maybe less so for a nocturnal reptile. As a result, I would suggest that you consider opting for the 13 watt version, rather than the more powerful 26 watt alternative.
The other concern – which is much greater – is that Exo Terra seems to be changing the light produced by these bulbs but without updating their sales page. Some reptile keepers have bought the Repti-Glo 2.0 only to find that the packaging states it doesn’t produce any UVB at all.
This would seem to a contradiction in terms – a UV lamp that offers no UBV. That said, to be fair, it does produce UVA light, which I guess is better than nothing.
All the same, with these concerns having been raised it may be better to consider an alternative UV light that does offer at least a measure of UVB light.
Exo Terra Repti-Glo 5.0 Compact Fluorescent Tropical Terrarium Lamp
In most cases the Repti-Glo 5.0 will provide useful UV light for a distance of around 12” / 30cm. While this might not sound like much – especially if your cage is some 18-24” (45-60cm) in height – with their stick toe pads crested geckos are able to scale the walls of their cage to bask directly under the bulb. By placing a piece of cork bark closeby you will make this process all the easier for your pet.
All in all this is a good little bulb for the caring crestie keeper looking to supplement the ultraviolet light that their pet is receiving.
What Is the Best Crested Gecko UV Light?
The market for reptile UV lights is quite competitive, which has been effective at keeping costs to a minimum. As a result, all three of the UV bulbs discussed are quite competitively priced. Cost therefore shouldn’t be a factor when deciding on which bulb to use.
Personally I have been using the Exo Terra Repti-Glo 5.0 for some months with great results, but I am also keen to experiment with the Zoo Med ReptiSun 5.0 to see if there is any noticable difference in behavior.
I personally feel that either of these two represent the best crested gecko UV lights currently on the market.
Setting Up Your Crested Gecko UV Bulb
Before we finish off this guide there is one more question that you’ll need to ask yourself – how will you actually for your UV light to your crested gecko vivarium?
Remember that UVB light doesn’t pass through glass or perspex, so you’ll either need to place the bulb inside your crested gecko’s tank, or use a tank with a mesh lid through which you can shine the light.
These days the most popular cages for cresties are probably the glass Exo Terra vivariums. Fortunately Exo Terra make specific hoods designed to fit over their Exo Terra glass vivarium range, complete with a bulb holder and on/off switch.
If, like me, you’re using an Exo Terra cage for your crestie things therefore couldn’t be simpler – just buy a hood of a suitable size and screw in your UV bulb. Personally I’m using this hood with a Repti-Glo 5.0 bulb right now with good results.
Lastly, please be aware that the UV output of any reptile lighting setup falls over time. At present it is recommended that your bulb is changed every six months, even if it still seems to be producing visible light. Doing so will ensure that your crestie benefits from the maximum amount of UV light at all times.
If you have any further questions about crested gecko UV lights, or you have any experiences you’d like to share then please leave your thoughts in the comments section below…
Photo by Chris Parker2012 
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I have been using the reptisun 14″ T5 HO Terrarium hood with the 12″ 5.0 T5 HO UVB bulb for the past 5 months. However, the hood recently stopped working. It has been suggested that the issue is water damage – the hood sits on top of the mesh lid of my terrarium and therefore is too close to the humidity in the terrarium. Does this make sense? Would the compact fluorescent UVB bulbs you mention above also sit on the mesh lid and have the same susceptibility? These lights and fixtures are very expensive and I don’t want to have to keep replacing the fixture….
Hi Cathy – yes most bulbs will sit close to the mesh, as it helps to ensure the UV light permeates into the tank. That said, I’ve been using the setup described for the last 9 months or so, on several tanks, and I’ve had no issues at all. Perhaps you were just unlucky – or the humidity wasn’t to blame?