Occasionally, we stumble into a substantial online argument about bearded dragon care. There are some strongly held opinions out there, and that’s understandable as people are talking about their pets!
One of those arguments, which gets repeated often, concerns where to place the UV ballast/fixture in relation to your bearded dragon’s tank.
One side says uv light location should be above the mesh screen at the top of your enclosure is perfectly fine. The other says that the screen stops too much UV light from reaching your bearded dragon, and the light should be located inside the tank below the screen hood.
So… Which one is correct?
Do You Need To Move Your UV Fixture Below The Screen Top of Your Bearded Dragon’s Tank?
If you use the correct type and size of UV light, you can place them above or below the mesh on top of your bearded dragon’s enclosure. While the screen will filter out some UVB rays, the correct size bulb and fixture will provide more than enough UV light to keep your beardie healthy.
The short answer is not to worry about it!
Use the right size and type of UV bulb and fixture, and the screen top of your enclosure will not make a big enough difference to matter.
So why do some people get so bent out of shape about moving their UV light below the screen? Because if you measure the UV output, there is a sizeable difference in the amount of UV rays that make it to your bearded dragon. We’ve seen measurements that show as much as a 40% difference.
So, technically, it is better to have it below the screen. There is more UV light that way, and UV is very good for your beardie.
The thing these folks never point out is that there is still a very healthy amount of UV making it to your bearded dragon, even with a mesh screen in the way!
In other words, they aren’t comparing levels that are too low with healthy ones. They are comparing healthy to more healthy. Either can work for your bearded dragon!
Another important note is that you can have too much UV.
Placing the UV fixture under the screen would necessitate a UV meter to ensure you aren’t providing too much UV to your beardie (always aim for no more than a 7.0 UVI reading on your meter – to find out more about UV meters, see our article here).
Tank Size And UV Light Location
Since we started Beardie Bungalow, we’ve measured the UVI in over 40 different bearded dragon enclosures. We’ve only recommended moving the UV light under the screen top in three cases.
All three times were in enclosures that were taller than “standard.”
Typically, a bearded dragon tank is 18-24″ (46-61 cm) high. An appropriately sized UV light will effectively cover the entire enclosure at the height.
Once you go taller than that (like this one), it becomes harder for UV rays to reach the bottom of the enclosure, even with the right type and size of light.
So, if your beardie’s tank is over 24″ high, you may want to consider mounting their UV fixture inside the tank and not above the screen top.
How To Know For Sure
If you have an 18-24″ high enclosure and use the bulb type we recommend, you can safely set your fixture up above the top of the tank and over the mesh.
If you are using a different type of light or an enclosure taller than 24″, you’ll want to check and see if your UV levels are within a safe range.
Do this with a UV meter (the industry standard for people keeping beardies as pets is the Solarmeter (check Amazon’s price here). This is the most affordable, accurate UV meter on the market.
You want to ensure the UVI (ultraviolet index) is between 4.0 and 6.0. It should read closer to 6.0 near the light itself and 4.0 furthest away. 7.0 is about as high as you want it. Anything over that is too much.
We cover whether or not you actually need a UV meter in this article, but the short version is you probably don’t.
Using the right size tank, fixtures, and bulbs is much easier than trying to compensate for alternative setups.
The Verdict
The world is full of people who want to do things differently. We run into that all the time when people ask us about unusual and imaginative tank setups.
If you are an experienced beardie owner or reptile keeper, go wild! You probably already have a UV meter and all the knowledge you need to work outside the standard guidelines.
But if you aren’t, stick with a recommended setup like we list here.
If you do that, you won’t have to get involved in online arguments about what % of UV rays are filtered out by the mesh top or other such nonsense.
You’ll also have a healthy bearded dragon with plenty of UV light!
Further Reading and Sources
Vitamin D and Skeletal Development of Young Bearded Dragons with Different UV Exposure Levels.
The mesh top reduces UV strength by as much as 40%. That’s why most people recommend mounting the light under the mesh. Why are you saying it doesn’t matter? 40% is a huge reduction.
I’ve seen that number in many articles, but what you rarely see are the actual readings. If inside the tank give you a reading of 7.0 (the max safe level you want) and outside is 40% less, that’s a reading of 5.6. That’s still firmly inside the desired range of 4-6, it’s even at the high end.
The truth is that of all of the setups we’ve seen, most have the UV light on top of the mesh as there isn’t a great way to mount the light inside of most tanks. All of those tanks measured just fine and in the healthy range on our UV meter.
That said, we never say not to put it inside. If the readings aren’t higher than 7.0, go for it!
How would you even hand it under the screen? Wouldn’t that be too close to the beardie? And what about the cord? I feel like setting it on top is better in almost every way.
I agree with all of that, it’s a giant pain with no benefit to put it under the screen top.