I totally agree, the Exo Terra 200 Coil
UVB bulb is a 26 watt
UVB bulb, so it's strong, but the issue when you're using it for a Bearded Dragon or other desert reptile that requires 13-14 hours every day of very strong, intense UVB AND UVA light is that if the tank is larger than like a 20 gallon long tank, you have to use special lamps INSIDE that tank to magnify the UVB and UVA light and reflect it throughout the tank for your dragon. So they usually end up getting both inadequate UVB and UVA light, then a calcium deficiency, then MBD, etc. Usually the bearded dragon owners that successfully use the Exo Terra 200
UVB bulb use is inside a special "Nano Lamp Fixture" with a large, metal reflector around it, and they do not have it obstructed by any type of mesh lid. So just having that coil
UVB bulb inside a regular deep-dome or clamp-lamp fixture on top of a mesh lid is most likely resulting in a UVB and UVA deficiency.
I'd definitely be switching over to a T5 strength UVB tube, at least a 22" or 24" long T5 UVB tube or longer, in a T5-rated tube fixture with a metal reflector inside the tube fixture behind the UV tube to reflect the UVB and UVA light throughout the tank. He'll perk right up and his appetite will be much better. You can allow either the 22" or longer Reptisun 10.0 T5HO or the 24" or longer Arcadia 12% T5 UVB tube sit on top of the mesh tank lid as long as his main basking spot/platform is within at least 11" of the tube. The T5 UVB tubes only need to be replaced once a year.
I'd also completely ditch the CHE, at least during the daytime, as Bearded Dragons are desert reptiles that naturally get all of their light and heat from the bright, natural sunlight above them. So you should ideally have both a long, strong T5 UVB tube sitting right alongside a high-wattage, bright-white colored Basking Bulb (usually a 100 watt Halogen Indoor Flood Bulb or a bright-white colored reptile basking bulb will get both the Basking Spot Surface Temp and the Hot Side Ambient (air) Temp within the correct 105-110 degrees for baby/juvenile or 100-105 degrees F for an adult for the Basking Spot Surface Temp, and between 88-93 degrees F for the Hot Side Ambient Temp), and then after you get both of those temps within the correct ranges, then measure the Cool Side Ambient Temp, and if it's not between 75-80 degrees (really as long as it's at least 70 and no higher than 80 you're fine), then you can simply add a much lower wattage, bright-white colored Basking Bulb over the Cool Side of the tank in either a separate Dome or Clamp Lamp fixture (usually a 30 watt over the Cool Side in addition to the main 100 watt over the Hot Side will get the Cool Side Ambient Temp around 75 degrees).
In addition, you do not want his nighttime temperature to be "steady", or anywhere near his daytime temperatures in order for him to sleep soundly and comfortably. The Australian Desert gets very cold at nighttime (in addition to being Pitch-Black), and as long as his tank stays at 65 degrees at night he's fine. Actually, they seem to be most comfortable at night when their temps are between 65-70 degrees. A lot of people think that they need to be kept in the 80" or higher at night, and this is totally disrupting their sleep. And a 100 watt CHE is way too hot for nighttime!!!! Think of it this way: Most people keep their homes at least around 60 degrees or higher at nighttime, and this is all it takes to keep your dragon's tank at 65 degrees or higher. If by chance his tank is, say, around 55 or 60 degrees at night, then you only need to bump up his nighttime temps 5-10 degrees!!! This would only require a CHE that is 10 watts max!!! Most people need no nighttime heat source at all though, because their homes are kept at 60 degrees or higher at night anyway.
Also, what is that substrate you have in the bottom of the tank? I can't tell what it is, but it looks to be some type of "Loose" substrate, such as a colored Calcium Sand...
