Reptile Lighting & Heating Guide
Getting UVB and basking heat right prevents most of the health problems we see in captive turtles, Bearded Dragons and Water Dragons — here's how to choose and set it up properly.
This guide applies across species — everything below is relevant whether you're keeping a turtle or a Bearded Dragon or Water Dragon. Get lighting and heating right and you'll avoid the two most common preventable conditions we see: Soft Shell in turtles and Metabolic Bone Disease in lizards.
Reptile Lighting
When keeping reptiles in a captive environment, we need to provide artificial sunlight — and not just any old light will do. Pet shops sell reptile-specific lights in a range of shapes and sizes, so it's worth understanding exactly what your reptile needs before you buy.
UVA / UVB — What Does It Mean?
Natural sunlight's UV spectrum has three parts: UVA, UVB and UVC. UVA and UVB are both essential to a reptile's wellbeing:
- UVA is in the visible light range and drives normal behaviours like feeding and activity.
- UVB is a non-visible wavelength that allows synthesis of Vitamin D3, which helps process calcium and prevents Soft Shell in turtles and Metabolic Bone Disease in lizards — a condition particularly common in Bearded Dragons and Eastern Water Dragons kept under incorrect lighting.
Which Light Is Right for My Reptile?
Some reptiles are "sun-worshippers" — including Bearded Dragons, Eastern Water Dragons, and many turtle species, especially Red-Eared Sliders. In the wild, these animals spend many hours a day exposed to high UVB levels, and they need the same in captivity. If you're keeping any reptile in New Zealand, assume you have a sun-worshipper on your hands and buy accordingly.
| Fluorescent tube rating | UVB output | Recommended? |
|---|---|---|
| 2.0 | Low | No |
| 5.0 | Moderate | No |
| 8.0 | High | Yes |
| 10.0 | Highest | Yes |
These numbers represent the percentage of UVB wavelengths a tube gives off — the higher the number, the better for your reptile's wellbeing. Whatever reptile you're keeping, we recommend an 8.0 or 10.0 rated bulb or tube. Compact UVA/UVB low-energy bulbs vary — some list a UVB percentage and some don't, so it pays to read the fine print and choose one that states it clearly.
Intensity & Placement
Glass filters out 95% of UVB. Fly mesh filters out 30%. Turtle tanks are best kept without a lid, and lizard lights should be mounted inside the enclosure, so your reptile gets the full benefit of the UVB produced.
There are two types of reptile UV bulb: UVA/UVB fluorescent tubes, and compact UVA/UVB low-energy bulbs. Whichever you use, the distance between your reptile's sunning area and the bulb should never exceed 300mm — the further away your reptile basks, the more UV output drops off.
Tubes and compact bulbs also need replacing on the manufacturer's recommended schedule — usually annually — because UVA/UVB output declines well before the bulb stops producing visible light. A bulb that still lights up can be giving your reptile zero UVB benefit.
How Much Light Per Day
Provide a minimum of 10 hours of artificial light per day. The simplest way to manage this is to turn the light on when you get up in the morning and off when you go to bed.
Reptile Heating
The detail below is aimed primarily at heating for Australian dragons (Bearded Dragons and Water Dragons).
Dragons need a basking spot in their terrarium that reaches 35°C–40°C, set up at one end of the enclosure so your dragon can thermo-regulate — moving toward the heat when it needs to warm up, and away from it once it's ready to be active and feed, digest, and go about its day. Never heat an entire enclosure to 40°C: with nowhere left to cool down, your dragon will overheat and can die.
An enclosure with no cooler zone gives a reptile nowhere to escape excess heat. Always run a temperature gradient, never a uniformly hot enclosure.
Ceramic Heat Lamps
A ceramic heating element designed to give off heat without light, available in a range of wattages.
- Must be used with a probe thermostat to prevent overheating the terrarium and your dragon.
- Must be mounted inside a mesh protection cage — surface temperatures exceed 200°C, enough to cause serious burns to your dragon or to you on accidental contact.
- Must be used with ceramic fittings, since they run very hot.
- Bulbs are a bigger upfront cost but last approximately 10,000 hours of use.
Recommended basking temperatures: 35°C for Bearded Dragons, 30°C for Water Dragons.
Infrared Heat Bulbs
A red-coloured infrared reptile bulb that reflects heat, available in various wattages.
- Best used without a shade — this prolongs bulb life.
- Must be mounted inside a mesh protection cage to prevent burns to your dragon or to you.
- Must be used with ceramic fittings.
What to Avoid: Heat Rocks, Heat Pads & Under-Substrate Heating Cables
We avoid heat rocks, heat pads and under-substrate heating cables. Reptiles are built to absorb heat on their backs from above, not through their bellies — you'll never see a reptile lying on its back, feet in the air, soaking up the sun. There are also documented cases of reptiles being burned from below when these products' thermostats malfunction.
Frequently Asked Questions
What's the difference between UVA and UVB for reptiles?
UVA is visible light that drives normal behaviours like feeding and activity. UVB is non-visible and allows Vitamin D3 synthesis, which helps process calcium and prevents Soft Shell in turtles and Metabolic Bone Disease in lizards.
What UVB percentage bulb should I buy?
An 8.0 or 10.0 rated fluorescent tube, regardless of species — these give the highest UVB output available in New Zealand pet stores.
How far should a UVB light be from my reptile?
No more than 300mm from the basking spot. UVB effectiveness drops sharply with distance.
How often should I replace my reptile's UVB bulb?
As per the manufacturer's recommendation, usually annually. UVB output declines well before the bulb stops producing visible light, so a working-looking bulb may be giving no UVB benefit at all.
What temperature should a dragon's basking spot be?
35°C–40°C, positioned at one end of the enclosure so the dragon can move away to cool down. Recommended basking temperatures are 35°C for Bearded Dragons and 30°C for Water Dragons.
Are heat rocks safe for reptiles?
We don't recommend them. Reptiles absorb heat through their backs, not their bellies, and there are documented cases of reptiles being burned when heat rock or heat pad thermostats malfunction.
Not sure which bulb or heater suits your setup? Get in touch — we're New Zealand's reptile specialists.