How to select the right lighting for your reptile
The UVB lighting that we provide our reptiles with is used to replicate natural sunlight experienced in their native environments. The sun emits 3 main sunlight rays, UVA, or visible light, UVB which can be absorbed over the skin and converted to vitamin D3, and UVC, which is the harmful part of sunlight that causes sunburn but is mostly blocked by the ozone layer.
Vitamin D is of particular importance for reptiles, as it allows them to properly make use of the calcium we provide to them via their diet. Without adequate vitamin D3 from both appropriate lighting and dietary supplementation, reptiles can develop serious, and even fatal health issues such as Metabolic Bone Disease (commonly known as MBD).
Different species of reptiles require different amounts of UVB, usually dependent on their native environment and behavioural patterns, for example, a diurnal arid species will require more UVB than a nocturnal rainforest species, as it would naturally be exposed to much more UVB in its native habitat. However, no matter the species or their required UVI, good quality, full-spectrum lighting is essential.
How we measure the amount of UVB emitted by reptile lighting
We usually measure the amount of UVB produced by the sun, or specific lighting using a Solarmeter, which will provide you with an Ultraviolet Index (UVI), usually somewhere between 0-6. The resulting UVI from any UVB lamp will differ depending on the distance, for example, a 12% UVB lamp may produce a UVI of 4-6 when measuring 30-45cm (12-18") away from the lamp, or a UVI of 3-4 when measuring 40-60cm (15-24") away from the lamp.
This means that when selecting the UV lighting setup for your pet reptile, not only do you need to consider the strength of the lamp itself, but also the distance between the lamp and your reptile's highest basking area. All UVB lights will have a minimum safe distance, which is the minimum distance between the lamp and your reptile's head before the levels of UVB become unsafe.
Types of UVB light sources for reptile lighting
Reptile UVB lamps come in four main forms, compact UVB bulbs, fluorescent tubes such as T8 tubes or T5 tubes and mercury vapour bulbs.
Compact UVB bulbs are similar to a standard coil light bulb and are usually screwed into light fittings. They have a lifespan of approximately 6 months before the amount of UVB outputted is negligible and the lamp needs to be replaced (please note, expired UVB lamps will often still emit visible light or UVA, but will no longer be producing the important UVB, so it is important to keep a note of when you installed the lamp, or to regularly test the UVB output with a Solarmeter).
T8 UVB tubes are strip lights, more suited to longer enclosures where you need the UVB to cover a larger area. However, they are not as powerful or effective as the more modern T5 lamps, and also have a lifespan of around 6 months, similar to compact lamps. In most instances where you might use a T8 lamp, a T5 lamp will do the same thing, but better, however, at smaller distances (perhaps your enclosure is very low), T8s may still be a suitable choice.
T5 UVB tubes are similar to T8 tubes, although they are slimmer tubes, produce more UVB per wattage of electricity, making them both more powerful and more energy-efficient, and have a lifespan of around 12 months before they stop emitting adequate amounts of UVB.
Mercury vapour bulbs are slightly different, these are similar to standard heat lamps and screw into light fittings, but not only do they emit UVB, they also provide heat to your reptile. These bulbs cannot be controlled by a thermostat which means they are likely to overheat if used in enclosed spaces, so they're best used over an open-topped enclosure such as a tortoise table, where they can be moved higher or lower as required to reach the optimum temperatures and UVI.
How do I know which type of UVB light to use?
In almost every instance, the best option in terms of space-saving, cost-effectiveness and energy efficiency will be a T5 reptile lighting unit. If you have a very small reptile in a very small enclosure, you may struggle to find a T5 light small enough, in such instances, you may opt for a compact UVB bulb. Whereas, if you have a tortoise on an open-topped tortoise table, you may opt for a mercury vapour bulb for ease.
How do I know which strength of UVB light to use?
To begin with, you need to research the reptile you choose to keep and find out their required UVI. Once you know this, you can assess the different types of UVB light and the UVI they will provide at different distances.
For example, Bearded dragons require a UVI between 4-6, this means that you can use a 6%/ zone 2 T5 tube, or a 12%/zone 3 T8 tube at 25-30cm (10-12") above the basking zone, a 12%/zone 3 T5 tube at 30-45cm (12-18") above the basking zone, or a 14%/zone 4 T5 tube at 45-60cm (18-24") above the basking zone. Note here, that if your light is any higher than 30cm (12") from the basking zone, a T8 tube will no longer be suitable due to the low levels of UVB emitted in comparison with T5 tubes.
In contrast, many crepuscular species such as Crested geckos or Leopard geckos require a much lower UVI, doing best with a UVI between 1-2. This means that you can use a 6%/zone 2 T8 tube or a 7%/zone 1 T5 tube (note the 7% here refers to Arcadia's ShadeDweller range, produced specifically for crepuscular animals and the slightly higher percentage does not correlate with a higher level of UVB output - these still emit less UVB than a standard 6% T5) at 25-40cm (10-15") above the highest basking zone. Whereas if the light will be closer to 40-45cm (15-18") above the basking zone, a 6%/zone 2 T5 tube will be required.
Why would I use LED lights for my reptile?
LED lighting for reptiles is most commonly used in enclosures that incorporate live plants. This is because most UVB lighting focuses more on UVB output than UVA output, which is the more important part when it comes to photosynthesis in live plants. LED lights, however, prioritise visible light output, making them perfect for use as growth lights.