​Is T5 or T8 lighting more suitable for bearded dragons?

​Is T5 or T8 lighting more suitable for bearded dragons?

At Internet Reptile we are always looking for ways to promote and increase the health and wellbeing of the animals we care for ourselves as well as those belonging to keepers who seek our advice.

Two decades of experience has taught us that the best way of doing this is to embrace change and adapt with the latest innovations and scientific findings. Our approach is backed up by the fact that the vast majority of health problems we see in captive reptiles are a direct result of keepers following bad advice which is often based on a stubbornness or reluctance to change outdated care methods.

The use of T5 lighting is recommended by the most respected experts in this field who we refer to when we set out our own care techniques and guides. One of the most accessible and easy to use sources on this subject is the  Arcadia Interactive UV guide. This covers over 130 species (including bearded dragons) and helps establish exactly which lamps are suitable for each species as well as the height at which they should be installed.

We would also recommend reading the new book ‘Fire-The Sun, its use and Replication in Reptile Keeping' by John Courtney-Smith MRSB, (Head of Science and Innovation at Arcadia Reptile). This covers the subject in a fantastic level of detail and is, in our opinion, an absolute essential read for hobbyists who want to gain an in depth understanding of the subject.

At Internet Reptile we made the switch from standard output T8 to high output T5 for our bearded dragons over 2 years ago and haven’t looked back since. We raise hundreds of strong, healthy bearded dragons every year with absolutely no health concerns such as metabolic bone disease ‘MBD’, eye issues nor any other conditions commonly associated with poor quality, and/or improperly fitted lighting. For more information on how we do things please see our in depth  bearded dragon care sheet.  

With this in mind and alongside the recent product cost reductions (such as the Arcadia ProT5), meaning that a T5 system no longer costs any more than an older T8 system, we now only sell our own bearded dragons and bearded dragon setup kits with T5 lighting systems.

With a wealth of outdated or incorrect information available to anyone with access to the internet we asked John Courtney-Smith if he could help provide any further insight into this subject and help tackle some of the myths that our customers are presented with when they seek to learn more about this subject online. We had a great response from John which we published in full below.

“This really is very simple maths, however, getting it wrong can lead to animals being chronically under, or even over supplied. The fact is, YES there is a use for T8 lamps in certain areas. But generally, for other species now. We must provide a level of energy that supplies for the core developed need of every species and in the way that this species has developed to use it. When a species has developed over vast periods of time to use high quantities of full-spectrum terrestrial daylight, it makes it very hard for a tech that is ‘low output’ by nature to be able to supply for this need safely or effectively. T5 is a revolution in this respect as it removes almost all of the historic limitations to care. They are flicker free, much better for sensitive reptile and human vision. They produce more visible light, this in of itself will help a dragon to find the basking spot properly as the brain is activated by qty of light (lux). See the various studies and papers regarding the pineal eye, its use with the sun and the subsequent positive affect that high levels of visible light have on the brain. Plus High Output T5 lamps are able to project a more usable quantity of UV energy to a safer distance, this reduces greatly the risk of eye infection caused by the glare associated with lamps fitted in close a proximity to the eye.

Firstly, we MUST provide a level of energy from light that provides to the long term developed need of any species. We use the unit of measure called ‘UV Index (UVI)’ for this as it allows us to take readings from the wild and to then replicate these in captivity accurately. If we underprovide energy in terms of ‘index’, we reduce the body’s ability to start and to maintain properly the many cycles and processes related the natural use of UV. If we over provide it, we override the developed level of protection that exists within the skin and increase the risk of burns and genetic change. The watch point here will always be, to provide enough energy in a safe and measured way per species and per individual enclosure.

In terms of quantity of light, basking animals such as bearded dragons have developed over vast time in order to take everything that they need to thrive from the environmentthat surrounds them. This includes food and water, but also the quantity of visible light, heat (being terrestrial Infra-Red) and UV. They have developed a thick protective scale covered skin and protruding bony eyebrows (enhanced orbital bones) which provide a further level of protection to the eye also, (built in sunshades). As such, we can see a use for and a level of protection against all of the terrestrial wavelengths of sunlight and to the levels that are used/experienced in the wild. This is the energy that is available to them and as such they have developed consistently over time to utilise it in the best possible way, it has therefore become their ‘level of need’. The sun itself produces many times more visible light than even a very well reflected T5 lamp. The quantity of light used in vivaria is not an issue, if fitted correctly. In fact, the correct type of halogen heat lamp is far brighter. Typically, we do not provide enough visible within vivaria, certainly even a well reflected T5 is not able to replicate the quantity of light that is required to interact with the brain as it does in the wild. Much research and product development is already underway with regard to this issue. It has now become common for keepers to use Arcadia JungleDawn LED lamps within arid vivaria in order to further increase the quantity of light and thus inspire a further level of natural behaviour.

The only risk of exposure to these lamps arrives from improper fitting. i.e., a lamp hung down into a vivarium where the lamp becomes fitted side on to the eye, or in which the height of decoration allows the dragon to bask at a distance that is too close to the lamp.Every light source, no matter its type, tungsten, halogen, UV, LED, if it is bright enough and fitted side on to the eye will cause a level of irritation to the eye leading to possible infection, this is glare induced photo-kera-conjunctivitis. The risk increases with UV lamps of every kind, be they T8, T5, SBMV etc as the eye would be bombarded with the energy contained in the photons within these wavelengths which could increase the risk of burns and cataracts. This is NON-NATURAL provision, harm caused by improperly fitted lamps, poor quality lamps and/or incorrectly designed enclosure furniture- this must be avoided.

There is also a risk from some cheaper lamps in which there is a heavy weighting towards low spectrum UV-B. As such these lamps are not terrestrially balanced between UV-A and UV-B and may even appear to emit a blue/purple hue. Worse still there is still the risk of unregulated imports that may produce harmful UV-C. These are all very real risks and should be taken seriously by all reptile keepers no matter the species that is to be kept. It is by understanding the needs of each species and the limitations and benefits of key pieces of technology that we are able to supply for their core developed biological needs.

Reptiles have developed to use the energy that is projected from above themselves. As such, our lamps must always be placed well above the head, whilst ensuring that we decorate our enclosures with natural items such as thick slates in a way in which the animal cannot climb to become side on between the eye and a lamp of any kind.

Here is an important point, T8 lamps project roughly half the energy of a good HO-T5. This equates to a halving of the useful distance between the lamp and animal in terms of optimum index projection.

We suggest that an optimum ‘wild-like’ level of exposure for a fully scaled Bearded dragon, whilst being provided alongside the core values of the light and shade method is up to UVI 4.00-6.00.This means that you can allow exposure at the very top of the basking zone to an index between these values and subsequently be sure that your animal is able to correctly obtain a quantity of energy that allows it to maintain its natural processes and cycles. By using the light and shade method we then also allow the animal to accurately and naturally self-regulate between the limited basking index, total shade at the cool end and a myriad of levels of usable energy in-between. It is this graduation of energy that is most useful as it will enable the animal to regulate its own level of exposure as and when it has need without the risk of oversupply, nor being able to use the lamp improperly.

To achieve this with a high % T8 lamp the distance between the lamp and the animal would be around 8” if the correct reflector was used. At this distance the dragon is being exposed very closely to the lamp indeed and we risk glare related eye conditions as stated above. Great care should be taken.

We can generate exactly the same level of usable energy with a 12% UV-B reflected T5 at 12-15”. The available energy is EXACTLY the same, but the lamp is further from the animal and therefore reduces the risk of glare. It is also worth pointing out that as the lamp is further away the footprint of illumination below the lamp will also be wider, thus increasing the animals ability to find a usable graduation of energy.

We can also increase the basking distance once more with the 14% DragonLamp. Again, the same level of usable energy produced by the T8 12% and reflector at 8” is produced by this very clever lamp but at 15-18+” from the lamp to the animals head, when seated at the top of the basking zone. Subsequently, the animal has access to the same level of usable energy but at a greater distance and over yet again an increased area. However, the risk of glare related conditions has all but disappeared.

This is particularly useful within the latest thinking for optimum sized dragon enclosures being 5’ long, 3’ high and 2’ wide. Finally, we have a solution to being able to provide our animals with the space that they need to demonstrate natural behaviour, enrich their bodies and minds (the 3 parameters of overall-nutrition) whilst being sure that we can supply for their core developed solar requirements.

In this way, we can use a lamp that is long enough to cover the whole body (as least nose to vent) but is not usually longer than half to two thirds the total length of the viv to properly supply the required level of energy. We should use a rock stack to create a wide basking zone under the area where the UV and heat lamps merge and provide a graduation of usable energy within the enclosure towards total shade at the cool area. In this way the animal self-regulates just as it does in the wild, and to a safe representation of the energy that is experienced in the wild

This is a topic that is covered in full in the book ‘Fire-The sun, its use and Replication in Reptile Keeping’

John Courteney-Smiths New Book can be ordered online now at ‘Fire-The Sun, its Use and Replication in Reptile Keeping’

Further information about lighting can also be found online at Arcadia Reptile

20th Jan 2019 Internet Reptile (with a special thank you to John Courtney-Smith MRSB)

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