What is too much UV for your beardie ?

from http://www.uvguide.co.uk/uvinnature.htm
Note the UVB flux for Alice Springs which is considered prime central bearded dragon native habitat.

Data for Alice Springs
Location 23°42′0″S 133°52′12″E.
Alice Springs is just South of the Tropic of Capricorn the town of Alice Springs straddles the usually dry Todd River (which rarely has flowing water in it) on the northern side of the MacDonnell Ranges. Alice Springs is located in Central Australia, also called the Red Centre, an arid environment.
In Alice Springs, in summer, the average maximum temperature is in the mid 30s (Celsius), whereas in winter the average minimum temperature can be 5.5 °C (41.9 °F), with an average of 12.4 nights below freezing every year.
The elevation of the town is about 545 metres (1,791 feet), which contributes to the cold nights in winter.
The annual average rainfall is 285.9 millimetres (11.3 in) which would make it a semi-arid climate except that its high evapotranspiration, or its aridity. Dry tropical woodland savannah.

Discussion of above graph
It can be seen that during most of the day in their natural range the microW UVB /sqcm is higher than 300. Peaking at just under 500 microW UVB / sqcm .
I've lived in CBD territory and seen them out ( hunting, foraging , basking) right through the day except on the very hottest days (can reach between 46 - 50oC there).

There are no commercial UV tubes or globes available designed for reptiles which will produce the levels of UVB beardies encounter in their natural range in summer , the UVB source would have to sitting right on the beardie's head or back to reach UVB fluxes higher than 300 microW / sqcm.

It's unlikely to that you can mount your UVB source (compact, T8 or even T5HO) too close.
And an MVB will literally cook the beardie before you get close enough to have even 300 microW UVB / sqcm.

IMO if you try to get about 180 - 200 microW UVB / sqcm at the basking spot you will be doing OK, I call this distance required from the tube or globe to the basking spot that achieves this UVB flux the OPTIMAL DISTANCE . (The OPTIMAL DISTANCE will be a lot closer than the EFFECTIVE DISTANCE.)

A good guide is shown below :



Here is some data for an 80W MVB from Arcadia.


The optimal distance shown here between the lines is determined by temperature. UVI readings you will note they are quite low for this globe's operating distance for a beardie's optimal basking temperature range..Hence the need to have a secondary UVA and UVB source (either a compact , or a T8 , or a T5HO tube positioned at the OPTIMAL DISTANCE for this UVB source).
ie if you are already getting 40-43 degCelsius at the basking spot with your current MVB, going up to a higher wattage MVB will not help (as you will simply make the basking spot too hot and beardie wont voluntarily go there) even if you manage to get the UVB to about the required level of 180 - 200 microW UVB / sqcm at the basking spot . So it proves counter productive with a single all in one heat+light+UVA+UVB source.

Very interesing subject.....I appreciate having the graphs + charts to look at occassionally [ which are difficult to understand for many people like myself ] to see that there are reference charts as well as input from someone who actually lives in beardie land.

I do believe though that there are bulbs that can be too intense at a close distance, especially with reflectors. Think of anther man made bulb, the tanning bulb. These can burn people as badly and more quickly than the sun. I personally know of a girl who had to be life flighted to a burn center after staying too long under tanning bed lights.

But back to beardie bulbs.....the amount of uvb they need is debatable [ and we KNOW they need a good supply ] and what sounds like is necessary in theory is not really necessary according to what some people believe. If I raised over 20 years worth of dragons that were healthy + did not develop MBD without always having the bulbs unobstructed by mesh and without ever having bulbs closer than 8" and never owning an Arcadia 12% or Reptisun 10.0 t5, then it shows that this method can still work. Proper heat and calcium supplements plays a big part.....it's all part of the big picture that contributes to a dragon's health. And I have used the MVB's exclusively on some of my dragons.

Maybe some zoologist / research student should do a study to determine the ABSOLUTE MINIMUM UVB with and without oral VitD3 supplementation, perhaps as a masters degree project.

My aim is to try to help develop best practice for beardie husbandry wrt Ca, oral VitD3, UVB flux and commulative UVB exposure.

It's is my view (based on the physics of exposure to radiation sources) that the effect is commulative and reptiles can sense when they have had enough commulative UVB (and UVA) exposure , at which time to move away from UV source or seek shade. This is supported by obvervations of my pet skinks and beardies behaviours and the behaviours of wild skinks in my yard, and other reptiles in the wild.

One thing that does need to be included in the discussion of "too much" is basking behaviors. Seeing random individuals out midday vs understanding hour by hour behavior of an individual for example tells two potentially different stories. Our captive environments very rarely replicate the different microclimates wild animals have to choose from as often are designed around the lizard basking all day with little option for posture change. It's one thing to recreate a wild UV level AND offer an environment the reptile can understand instinctively vs wild UV level and a poorly constructed habitat. As an example I was interested to learn was that dragons will seek midday refuge high up in trees to avoid heat - seems counter intuitive at first but it's actually cooler away from the hot ground.

There isn't many good studys about dragons specifically - part of that is funding and part is also the legalities of animal testing. It's been shown in panther chameleons that UV self-selection does happen, it's probaly common in many basking reptiles. Crepuscular and nocturnal lizards like leopard geckos and created geckos will bask given UV even if they don't "need" it. Snakes are rarely given D3 supplements or UV light but are shown to synthesize it with UV light. The Facebook groups reptile lighting and advancing herpetological husbandry both have good collections of publications and information (as well as some top notch experts).

ABHD for the sake of discussion/to play devils advocate - in the situation like you describe the criteria of health is based on lack of some severe level defficency problems (MDB) and assumption of fitness based on largely subjective metrics. From a personal annecdotal experience I have a D3 deficiency (especially in winter) and while outwardly I look and act healthy the effect on mood, sleeping patterns and overall discomfort is something of a hidden effect. This unknowable factor is my concern with the line of thinking that it's been enough in the past. Again, just a counter point not questioning your animals health or anything.

Tater I understand what you're saying, and funny thing is I myself was diagnosed with a D3 deficiency + take supplements to correct it. I spend a lot of time outdoors, too.

But what I was trying to bring to the table here is that something that a person may believe in theory [ such as the dragons NEED bulb X for good health at a distance of X and can only achieve it that way] is not necessarily proven in practice. The dragons that are often posted in the forums with MBD like symptoms come from all different backgrounds but many are set up improperly with the weaker compact/coil bulbs. Some never fully recover, some seem to get better when it's simply behavioural problems presenting [ going from not eating + being inactive to active + eating ] Others have problems that can't seem to be corrected even when in a seemingly perfect set up.

So I'm not knocking advancement in uvb lighting, I'm just saying that what some people feel is now necessary concerning lighting for your dragon [ and feel it can't achieve good health otherwise ] is not necessarily so. So if my dragons have been healthy in the set ups that I provided, then in practice , and not in theory, it was sufficient to raise them properly . In other words, why look for a problem where there isn't one ?

kingofnobbys, thank you for posting that. That's interesting.

I'm in FL (north of Sarasota) and I'm taking my beardie out between 1 and 2 for half an hour. She only stays in the sun for a few minutes and then moves to the shade. The remainder of the time she stays in the shade and goes exploring there.

I was wondering if the sun would produce too much UVB for her but according to your chart that doesn't seem to be the case. Maybe she just thinks the shade has more interesting stuff for her to explore. Plus she's probably still getting some UVB there.

That's just it, no one really knows exactly how much natural sun they would expose themselves to daily, how long during what time of day, and from month to month as the seasons change, etc And there are many variables.....if the dragon is on a tree trunk in full sun or partly in shade, etc.

Your dragon may have been too hot or just looking for something else to do as you mentioned. And some dragons may prefer to find a place to hide if they don't have a place to climb.

AHBD":1c669qnz said:

That's just it, no one really knows exactly how much natural sun they would expose themselves to daily

Click to expand...

I think you're right there. I watched the lighting videos from the guys that make the Mega Ray MVB: http://www.reptileuv.com/reptile-video.php?nav=h

After that I added another flood light so that there is a gradient where she can regulate her UVB and still be warm. She definitely moves around in these areas, sometimes directly under the UVB, sometimes away from the UVB and under the other bulb, sometimes in between where she would be getting morning UVB levels.

I think this is an important topic and we should continue to discuss it, push our knowledge, test ideas out. As a group we may be one of the larger entities focused specifically on the well being of bearded dragons so we should continue to get better for their sake.

From what I've seen so far, they are tough critters and can adapt to quite a lot. They can survive a wide range of environments which is a blessing and a curse. I've seen quite a few of them do well despite less than ideal conditions and some doing well despite downright awful conditions. On the other side of the coin, I've seen dragons fail to thrive even under excellent conditions. Lighting is just one (important) part of the puzzle. I think it should be a focus to provide the best we can either way. That said, I realize there is a gap between ideal and reality. It would be wonderful if every dragon owner could provide cutting edge setups and have even a reasonable amount of money set aside for proper equipment and care. While we should continue to research and find the best information we can, it's also important to do the best we can given each situation. If someone doesn't have the money for a T5 light or a large tank, then they don't have the money and will need to provide the best configuration they can with our guidance. If we can determine what each lighting option provides then we can try and get the most out of it.

As far as what is best or ideal, I think that is always going to be a moving target and that's a good thing. The more we can learn about their natural habitat and behavior, the better. The trick is trying to translate that into a healthy captive environment. Since most enclosures are relatively small and have a set on/off UV setting, it's tough to translate natural sunlight patterns directly. While UVI outside could easily reach 14+ at some points, it's not that high throughout the day. In a smaller enclosure it might be best to provide a moderate amount of UV across the day while providing gradients. The better the gradients and larger the space, the higher the UV output could be in areas of the enclosure in theory.

I've been trying to study behavior patterns in captivity by using different lighting across my house and just watching how Darwin uses it. It's obviously a very narrow study but it's something. I have his tank setup with a T5 and a gradient from about 5 down to 0. Outside the tank he has an MVB that is about 10'' above the ground and produces UVI of between about 7-8 directly under it. He will often bask directly under it but also tends to sit to the side of the beam where the UVI is lower but temps are similar. I have another MVB that is a bit higher but has a basking rock that allows him to get close if he wants to. The UVI varies from about 2.5 on the floor to about 5 or so on the rock. He will bask on the rock but not for extended periods of time. He spends time warming up there in the morning but prefers the higher UV source later in the day. I have a third light that is just a halogen basking light which produces up to 115f directly under it with no UVB. He spends as much time under this as his other lamps. He will sometimes bask directly under it and will sometimes sit to the side where it's a bit cooler. When he isn't under one of the three lamps, he patrols the house in fairly regular patterns. He seems to do well at room temperature (around 70 at the moment) for extended periods of time but will return to one of the lights to warm up in between patrols. In the afternoon he tends to sit to the side of his intense UVB lamp. It's 5:19pm and he is sitting at 100f and getting 3.5 UVI. He has moved several times within the last hour but has remained near the intense lamp.

I had him outside camping all weekend. He spent time on a beach with plenty of shelter available. UVI went up near 9 during the early afternoon. He spent some time sitting in direct sunlight and was content but he also moved around a lot and spent quite a bit of time under the canopy or at the edge of the canopy with partial shade. Again, this is a very limited observation but it shows that given options, he will move about and can handle intense light and also enjoys shade.

I'm not really sure how high to go with the testing but it's clear that he puts the variety to good use throughout the day so the more variety and more space that can be provided, the better. It's tougher to provide a wide variety in a smaller space so the small 40g tanks and smaller have different optimal specs than a larger environment. I will continue observing and will test different bulbs as I get my hands on them - both the output and the reaction to them from Darwin. Perhaps he will enjoy UVI up over 10. I wouldn't recommend doing that in a small or restricted space though.

What you describe with moving between the lights is very similar to what I've observed too. I also observed that right around sunset, she will go off and find a cool, dark place to sleep. (That's usually when we put her back into her viv.) But I thought it was interesting that she seems to know exactly when the sun goes down, even though she's inside and her lights are still on.

Refer to a T5HO 12% Arcadia tube in a reflector hood , mounted ontop a fine mesh / flyscreen lid and 18 inches from the bottom of a beardie viv.
No UV globe or tube designed specifically for reptiles produces as much UVA or UVB as bearded dragons are exposed to in their natural range for most of every day of their lives in the wild.

Ref to this : viewtopic.php?f=6&t=234801&p=1806497#p1806497

If it were stilling ontop of A FINE mesh lid in a viv 18in tall , the UVB will be only about 50 microW / sq.cm on the floor = (1-M)xP(x=18in))= (1-.4)x80 = 0.6x80 = 48 microW UVB/sq.cm which is very low and equivalent to early morning and late afternoon (within 1 hr of sunrise / set).

It's certainly good to provide proper uvb, very important for our beardies. It still should be noted that our captive dragons live longer than wild beardies, and even have done so before the t5 bulbs were being utilized.