Healthy Lighting (UVB) for Blue Tongue Skinks – Ep. 81

Light the World Hey guys, how much UVB is enough? How much
is too much? What skinks need what? What brands are best? What types are best? Are there dangers
and risks to UVB? How do you know you’re providing the correct amount? Find out today
in this video. Welcome to ReptileMountain.TV a channel dedicated
to evidence based reptile keeping where opinion is not fact. I’m TC Houston a former professional
AZA zookeeper and current skink and reptile breeder dedicated to providing quality information
to the global reptile community. If you are new please go ahead and hit that subscribe
button and the bell to ensure you don’t miss an upload. If you’ve been here before
and haven’t subscribed … get with it y’all? I want to start by saying there are products
on the market for UVB that are fantastic and products that can seriously harm your animals.
I’m not talking about those off the wall knock off brands either… I’m talking about mainstream
brands. So be sure to watch this whole video because your animal’s health could literally
depend in it. Alright what is UVB what is it not? UV stands
for ultraviolet and it refers the the wavelengths of light that are shorter than and just below
violet on the spectrum which humans can see. There are three types of Ultraviolet light
A B and C. For our purposes today were talking about
type B which is the specific type that plays a critical role in natural production of vitamin
d3 in reptiles. In really simplified terms our skinks blue
tongues, pink tongues, social and crevice skinks and many other reptiles depend on UVB
light from the sun to produce vitamin d3 which is a vector/cataylist/mechanism for calcium
absorption. Thus, no d3 no calcium absorption meaning
weak bones which leads to loads of problems including but not limited to metabolic bone
disease and even death. Therefore the use of UVB in D3 synthesis is
the most natural and primary method by which most omnivorous and herbivorous reptiles obtain
most of their vitamin d3 and maintain strong bones and overall health. What UVB is not. It is not a magical bulb
whereby you animal will be transformed into a
healthy, active, interactive,
breeding, thriving, Olympic gold medal winning creature simply because you turned on a special
bulb. UVB will not make up for any lack in other husbandry deficiencies. A crappy diet
is still a crappy diet, improper humidity is still improper humidity no matter what
light you shed on the problem…you get it…what light…uvb is light ahh okay…. I am not going to discuss whether UVB is “required”
for skinks. I will say it is the primary and most natural method of ensuring your animal
has d3. However, There is a multitude of evidence to support that blue tongues can live and
yes thrive without ever being given UVB. I have a whole video on that here so please
check that out and come right back. Let’s get to addressing those questions
we all have. How much is enough? How much is too much? What type do I use? What brand
is best? And so on… There are three commonly available types of
UVB bulbs in the industry, yes there are a few others but I’m talking about the main
three. The linear bulb the compact fluorescent bulb and the vapor bulbs sometimes call mercury
vapor bulbs. So each of these bulbs has specialized components allowing for the mercury in the
bulb itself to be charged to a point of producing Ultraviolet B waves. Each bulb type has a
specific designed purpose. The linear bulbs are designed to produce a steady even amount
of UVB across a broad lighted range. The compact fluorescents can provide localized areas of
UVB in stronger but in a more narrow area that often simulates a sun patch coming through
the trees. A mercury vapor bulb produces both strong UVB radiation in a more broad area
than the compact fluorescents but not as broad as the linear bulbs. Mercury vapors also provide
heat so they can serve as a basking heat source and UVB source. Many of the bulbs on the market
come self ballasted and work with either a specified fixture or a standard ceramic light
fixture. Within the linear bulbs there are two main
types T8 and T5 High output. The T8 bulbs are wider in diameter and produce a less consistent
and weaker UVB output than the more narrow T5 bulbs. T8 bulbs are the first kind that
was marketed to private keepes and seems to be getting phased out by the newer more powerful
T5 bulbs. As I shared in my Art of Reptile Keeping video
(point) the answer to what bulb to use certainly depends on the variables within the species
natural behaviors, enclosure type, the environment, and the keepers goals. An example of natural
behavior variables would be, my gidgee skinks (Egernia stokesii). Their wild counterparts
are often viewed out on rocks, logs, and tree branches in the daytime under the hot Australian
sun disappearing at midday but appearing again in the early afternoon. They do well with
basking areas that can be as hot as 120F surface temps and do well with UV amounts similar
to the bearded dragon. Whereas, an Eastern blue tongue may bask in the open early or
in a partially sunlit area for thermoregulation purposes taking in lower levels of UVB than
a Gidgee Skink or Bearded Dragon. An example of enclosure variables would be
my son’s Horsfield’s (or russian) Tortoise (testudo horsfieldii) has an open air tortoise
tub with a mercury vapor bulb. There is no barrier between the bulb and the tortoise
other than air whereas my Berber Skink have a ¼ hardware cloth aka screeen between the
bulb and their skin. Anything between the bulb’s surface and the animals skin can
affect the amount of UVB absorbed. Many newer bulbs are manufactured to mitigate screen
mesh as a barrier but none the less the enclosure and environment affects the type of bulb.
The further away from the bulb the animal is the less UV the bulb provides. So a really
tall enclosure and a really short enclosure will have different UV reading for the animals
even with the same bulb. Also cage furniture can affect the UV waves as well. Even this
tape measure affects the waves hitting this Solarmeter. So plant cover and cage decor
can impact the UV. Keeper’s goals also play a role in deciding
what bulb to use. An animal that requires high amounts of UV and heat may do best with
a Mercury Vapor Bulb if the cage set up allows for the bulb to not over heat the enclosue.
For example my Gidgee skinks fall into this category however I keep them in an exoterra
large low which is short. The lowest watt mercury vapor bulbs still are too hot for
my set up because I need the space above the cage for storange and don’t wish to hang
the bulb higher to reduce temps. So I use ceramic heat emitter for heat and a ZooMed
T5 High Output linear bulb for UV. The lite area of the cage have a UV gradient range
from 2.0-7.0 depending on location within the cage. What wouldn’t work would be a
compact florecscent “coil” bulb. They don’t put off a broad enough area for the
animals to get a truly quality gradient over a wide enough space like they would in the
wild unless I used several bulbs across the top and at that point my cost would be higher
to do that than for one linear bulb. How does one know what to get then? Fantastic
question! To answer that let me show you This This is a Solarmeter 6.5 and this is a Solarmeter
6.2r These are UVB meters that can measure the output of UVB coming from bulbs and even
the sun. Using these meters. The 6.5 specifically, a team of herpetologists from Texas Christian
University led by Dr. Gary Ferguson looked that the UV index uses and behaviors of several
species of reptiles to develop what is called the Ferguson Index or Ferguson zones. These
are general guidelines for what UV indexes are used by what species or types of animals.
So for blue tongue skinks, my bread and butter as you know… thier research says they fall
in between zone 2 and zone 3 requiring approximately a 1.1-3.0 UV index for UVB. So taking this
Soloarmeter and first measuring where my animal basks and how far from the bulb I can then
take a reading that allows me to know if I’m on track for a blue tongue skinks. How do you know what to get? First Consult
the Furgeson Zones, there will be links in the description to this and more research.
Once you know where your animal falls on the scale then consider your enclosure set up
or desired set up and make an assessment from there. If your animal is zone 3 or 4 consider
either a T5 HO bulb at 10.0 or 12% depending on the brand or a Mercury Vapor Bulb. If they
fall lower on the Furgeson Index look for a 5.0 or a 6% T5 or even a quality compact
fluorescent. There isn’t a wrong answer as long as what you buy puts out a UV index
that is within their zone and all other aspects of husbandry are met. So What brand to I get? Quality bulbs will
produce UV as stated on the packaging. As far as I am concerned after multiple bulbs
and multiple tests I have confidence in only two brands. ZooMed and Aradia. I have tested
zilla, exoterra, zoomed, and acradia. In the past I have used Exoterra. I will say that
I made a horrible mistake trusting Exo Terra. In fact if you are using any ExoTerra compact
florecent aka coil bulbs and haven’t tested them individually with the solarmeter go turn
them off right now. Seriously pause this video and do that immediately. Not too long ago
I got a new solarmeter and was playing around with experimenting. I hadn’t tested all
my bulbs only a couple and they were fine. I was more interested in testing my T5 HO
stuff for the animals that requried those higher ferguson zone levels. But then I tested
one that wasn’t on an animal because I was trying to see how much UVI it put off after
a year of use. At 10 months I got bored a tested it.. It read a 15 UV Index! What the
???? I was blown away. I had been under the impression
the the mercury in the bulbs was supposed to degrate over time and that as it did the
bulb would put out less and less UV hence why they need replaced at 6 months and some
can go 12 months. But I NEVER imagined they’d be going up in UV output. So I went to the
experts and they are confirmed that poor quality bulbs can actually increase to dangerous levels
rather than decrease to nothing. After learning that I tested all my bulbs. They ALL increased
despite being less than 6 months old. Thankfully all but one were still in “safe” levels.
One however was too high. Thankfully I believe I caught it before any irreversible damage
was done. I no longer recommend ExoTerra bulbs for any use on living creatures unless you
are testing them monthly maybe even weekly with the Solarmeter. If you are not you could
literally be harming your animal without your ever knowing it. Here is what they say is
what this bulb produces on the packaging. Here is the reading. 4 times higher than what
is stated. Here is another. And another. And another. And yes this is a consistent result
from many new bulbs after running for over 100 hours!!! Like I said if you haven’t
personally tested it with a solarmeter turn them off NOW!!! What do I use? I use Acradia and ZooMed T5
High output linear bulbs on my Gigdee Skinks and Berber Skinks and my tortoise. The Arcadia
for the Berber is a 6% and the ZooMed is a 10.0 and the Arcadia for the tortoise is a
12%. They are reading perfect for these animals and have remained consistently. For my son’s
tortoise I use a zoomed Mercury vapor bulb which is also reading perfect. For my blue
tongues I use ZooMed reptisun mini 13w 5.0 compact bulbs which provides a square foot
region in the cage of about 1.5-2.5 UVI through the mesh. I also measure this on a weekly
basis now. I’m no longer taking chances with this crazyiness. To recap everything. There are three main
types of bulbs. Consult the Ferguson Zones and purchase accordingly. I only recommend
two brands ZooMed and Arcadia. And if you are using UV and don’t have a solarmeter
(I’m not paid to say this) you should. It is the only way to know what you are buying
isn’t radiating your animals. One last thing…I know several folks are
going to ask what about if I have this this and that what light should I buy. I’m not
going to tell you becasue this video has been all about how to figure that out on your own.
So you may need to consult other sources is this one isn’t enough but I’m not going
to tell you…Sorry. Thank you guys for watching. Look another
one of my videos it right down there. Go watch it! Thank you to my views, subscribers and
most of all my Patrons. You are awesome. Remember, opinion is not fact.


  1. Hey TC, I’d love to see you make a care video on the Gidgee skink. Great video btw!

  2. Thank you so much for your information. I have not switched to UVB yet because I didn't have a solarmeter. It is interesting and alarming to see how deep the issue truly lies, though.

  3. Thank you so much!!! I was excited when I saw the title, this answer some of my questions. I honestly wasn't aware that UVB strength exposure depended on the activity of the animals. The only thing I knew was that 10.0 was for arid species and 5.0 was for tropical species (can't remember what numbers exo terra use). Also really thank you for the warning on exo terra. My Columbian tegu was on one (now I shut it off) fortunately she has been slowing down and been in a kinda mild brumation so she hasn't been fully expose to it lately. My bearded is on zoo med all ready so I was relief.
    Again always good to watch your video, it is very informative!

  4. Hey, TC, great video. Been wanting to try Arcadia products but having difficulty finding them from US sellers. Where do you get yours? May be on your site, but if so I totally missed it. Thanks!

  5. lovely! I love this guy, always shining light on reptile matters. You are my guru, ya know? I always check other sources but still you are the most complete one on matters.

  6. So I recently got a Indonesian tiliqua giga and was wondering what should I feed him? He’s 6 months old and currently feed him cat food with some veggies and fruit. Should I change it?

  7. you have the best collection of skinks out there. can you do an all my pets vid.

  8. Thank you for doing this video. All very important information that people should put serious thought into!

  9. I was under the assumption that the uvb output would decrease overtime as well. I'm ordering a solar meter right now. Thank you helpful as always

  10. Amazing video. Good information and easy to understand and apply.

  11. Great info as always!

  12. Holy cow!! This is so fascinating. Love your channel! Always very informative and extremely helpful!

  13. Great info thank you

  14. I have a 10.0 uvb desert Exo terra bulb on for only 5 hours a day because I give d3 supplements would this be dangerous for a blue tongue?

  15. Extremely informative video 🙂 I have kept reptiles for a few years and I definitely think anybody keeping reptiles that are using UVB needs a solar meter. They are expensive, but definitely worth it in the long run. I really appreciate the fact that you emphasize people need to do trial and error. Sometimes it takes a little adjusting to get exactly what you need. Thank you TC.

  16. This is incredibly helpful! I had no idea the exoterra bulbs increase to dangerous levels over time! Thank you thank you thank you!

  17. Thank you for the informative video! I’m glad my ZooMed T5 10.0 is good for my Gidgee Skink. Speaking of, do you ever plan on making a care video for Gidgee Skinks in the future? It is very hard to find consistent information about them online!

  18. Thank you, you make the best and most helpful videos on the internet!!!

  19. I just found out I can get t5's and their reflectors here in Aus now,
    if I was to get them for my skinks what percentage will be good for them or do you just propose I get the reptisun compacts? I currently use Reptile one t8 5.0 on a reflector.

  20. I use for my TGE solar raptor with good UV results. Every reptile keeper most need a UV solar meter.

  21. Hey! Soo when you said, “Please turn off ExoTerra bulbs!”, I instantly looked mine up and low and behold I had to go turn it off (and am now looking for replacements). BUT re-watching it now, you said, “compact fluorescent (AKA coil bulbs)” and my UVB isn't a coil bulb it’s a linear bulb so does that mean it’s okay? I don’t have a solar meter and don’t know if (or maybe when) I’d be able to get one since they cost quite a bit (especially since I’m just 16 and don’t work at Maccas). I’ll leave it off and continue looking for replacements until you reply. (might also bring him out into the sun during the day cause its school holidays and I live in AUS and its summer so he will like that) [ExoTerra – 15W – 45cm/18" – UVB 100 for extra info] Also the T and then number rating thing doesn’t seem to be a thing in Australia can’t find that on anything here.

  22. Getting the the solarmeter 6.5r was the best thing i ever did for my reptiles, my problem with the exo terra bulb when i tested it was the low uvi and how the uv levals drops off very easily unless your reptile was directly under it. How much of an area of the enclosure should we be getting uv coverage? Im currently using arcadia uv flood 24 watt compact lamp

  23. This is a great video. I suggest your website and channel to every person that asks me about blue tongues. I've been reading through the info and maybe I missed it but, do you know what the ferguson zone is for a tiliqua gigas gigas?

  24. Wow, I had always been told that the UV output decreased with time, even unused in the box. Thanks for the info!

  25. **Further Details**
    The mercury in the bulbs does degrade. HOWEVER , so does the glass thats filters the radiation output. This is what appears to be causing the higher than desired UV readings. Just wanted clarify that the mercury itself isn’t miraculously increasing. 😁😁👍🏼

  26. Just curious does anyone know or have an educated guess if you could keep a blue tongue skin with a tortoise like a Herman's tortoise

  27. Does this only occur with the Exo Terra coil uvb bulbs or with the mercury vapour bulbs as well?

  28. So, I just rescued a blue tongue skink, it's my first bts, and I'm pretty exited about bringing him home. The problem is, and I'm kinda panicking about it, I have no idea what species he is. His previous owners keep him on pure sand, he can barely open his eyes and a few of his toes have fallen off 🙁
    I only have one picture of him, and that's of his face and one if his legs is showing too.
    I don't really know how to identify different blue tongue skink species, do you have a video on that or something? Cause I'm bringing him home in a few days and I don't want his care to be wrong.

  29. Thank you again for another evidence based video!

  30. Do the T5 bulbs produce heat as well? I recently got a Blue Tongue Skink and want him to have the best uv/ heat possible.

  31. Would that still be the same for the exo Terra heat bulbs as well?

  32. I have a question about housing a BTS with a bearded dragon. I have seen multiple people housing those two together but i wanna hear what you think. Becouse they live in the same country and need almost the same things in the enclosure i thought it was a good idea

  33. Your channel has been my holy grail.
    I am planning on getting a bts and this is my first reptile ever. Reading was a little confusing. I wanted to have an in depth explanation for everything and you have provided it!
    I WAS going to get my bts at an expo but you have educated me and I am steering clear from doing that. I applied to your newsletter and I am so glad I found a breeder and educator (you) where I'm not unsure if they are reputable.

  34. If there is a storm and the power goes out what battery back up system should I get or what do you use when your power goes out?besides that the video was very informational.

  35. What wattages are best for uvb?

  36. Is ginger juice smell safe for BTS?

  37. Hey been watching your videos for awhile now they have been really informative I'v been enjoying it a lot!
    I'v just recently gotten my first northern really exited, but while pick up the equipment I was told by an employ to leave the basking light on at night since it's a baby (they're about a month old) won't this mess with his sleep schedule?
    Thank you!

  38. What weight should you feed a baby BTS to? Please answer the young adult weight as well

  39. Is the exo terra halogen 50w basking bulb good or do you recommend a different halogen bulb?also for a exo terra tank 12 inches in high should I use a 10.0 compact because I know the tubs are 8” in high.Thanks

  40. Worried that this is asking too much… I know that is i a legit Channel. I now understand that I may have been “humanising” my reptiles! By this I mean on how you talked about how the animal shared no personal connections to their enclosure. What I was wondering if you can do, since I heard baby blues are usually born at around jan-feb (well at least here in Australia) so I wanted for a HUGE amount of time a video that is a time lapse of the blue tongue growth from newborn to adult. Might be asking too much so I’m sorry!!

  41. can skinks get scale rot and what is the difference between scale rot and just a dried out stomach ??

  42. So i had a question I've been watching your videos a lot trying to figure out what type of skink i have. She was just dropped off in a box at the veterinary clinic i extern out about a year ago. But they only did cats and dogs and didn't know what she was. But ever since i still can't figure out what type of blue tongue she is. And i want to give her the best possible care. And i was wondering if you'd have a guess at what type she was

  43. Im poor af so I put half my tank where the sun shines.It works tho. edit:Im from Indonesia.

  44. These videos are helping a lot I am planning on getting a Blue Tongue Skink at the Repticon coming to my area in the next month

  45. I thinking of making a bioactive eastern blue tongue enclosure I not sure where to start do you have any tips ?

  46. I was long hesitant buying a solarmeter 6.2 because of the high price (and most people who own reptiles don't bother with these), but now that I have it I realize how friggin important it is. Turns out that one of my exo terra lamps gave off relatively NOTHING, when I was planning for a bearded dragon who needs TONS. It was sold as a powerful desertic reptile lamp but even if you taped your lizard to it he still would not be getting enough… Same for my exo terra mercury vapor bulb which is supposed to be very powerful. Up to this day its still giving very sub par readings.
    I switched to Arcadia lamps, which are very powerful. Solarmeters also allow you to monitor your lamp's decrease over time so that you know when to change it instead of doing an automatic ''just in case'' change, so saves you money on the long run.

  47. Holy cow, I never knew exo terra compacts can get dangerous. I didn’t replace mine for over a year, who knows how dangerously high it is now 😨

  48. In all honesty if you cant take the time to find out what kind of bulb you need on your own maybe you shouldnt own something like these.

  49. This is such an important video that every reptile keeper needs to watch. Thank you so much for making this!

  50. Hi, I know you want us to find out which uvb to use ourselves however I just want confirmation on whether the uvb I'm using is too strong for my blue tongued skink as I've been told a few times it's too much, I have an enclosure which is 4'x2'x18"(WxHxD) however the substrate takes up about 5 inches, and I'm using a reptisun t5 10.0 uvb 39W strip light, is this okay or too much?

  51. Went to the Reptile and Amphibian Expo in Melbourne on the 2th of march to look around and buy things for a blue tongue lizard because i am getting one soon got a water dish and zoomed T5 Ho High output 39W REPTIsun 5.0 UVB and was told that it was the only lightning i needed for a blue tongue lizard is that true because i am not sure never owned a blue tongue lizard befor and don't want something bad to happen to it

  52. Beginner keeper friend's bearded dragon got metabolic bone disease from incorrect bulbs. They trusted a "starter kit" from Petsmart to include the correct lighting, not knowing this kit had no UVB bulbs, only heat. They were calcium dusting the food.

  53. Would an Arcadia 6% UVB T5 be ok for a 40 gallon tank?

  54. Oh wow I never thought some UVB's would increase the amount of UV when time passes, I'm getting a solar meter soon, one question TC, when it comes to you and your UVB lighting with northern blue tongue skinks, does the UVB cover the whole enclosure?, like is there a spot in the tank where it's shade? (excluding the hides), this might be irrelevant to this topic but some folks said that the UVB can't cover the whole tank, what's your opinion?

  55. Love your videos. At the beginning I thought your shirt said kinkaholic lol but it said skinkaholic. Sorry lol

  56. I LOVE your videos man! I’m going to get a Blue Tongue Skink when I save up the money. Do you sell them? If so, how much?

  57. Dude, just write us a book!

  58. UVB, etc. is a myth:


    Summary: Using a UV spectrometer, he shows a reading of 2.2 on a sunny winter day in Wisconsin. In the summer, the reading would be much higher, and in certain other parts of the world, it would be dramatically much higher.

    For a popular bulb that claims to be full spectrum with UVA and UVB (by the way, I can tell from the packaging that it's the Zoo Med AvianSun 5.0 UVB bulb), the reading is 0.6 a few inches away from the bulb, tapering off to 0.0 at eight inches. The manufacturer recommends a distance of 16-18 inches! At that distance, there's no UVB, and to get a miniscule amount, your dove would have to be blinded.

    *Regarding full spectrum lights (that don't claim to also produce UVA and/or UVB):

    * Full spectrum fluorescent lights are practically same as a typical fluorescent light that doesn't claim to be full spectrum.

    * Full spectrum incandescent lights–along with full spectrum fluorescent lights–also don't come close to daylight

  59. hey tc! great video as always. i have a northern bluey in an exoterra large and low tank, heat lamp on one side, and uvb on the other (i have the zoomed reptisun bulb). do you recommend getting uvb bulbs on both sides of the enclosure, or is one enough for his enclosure size?

  60. that light joke was just awful.. I love it

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