Word of advice Pet-store employees are dead wrong 99% of the time in a chain pet-store. If your lucky you may have that one guy/girl that has actual knowledge. Which is rare, I've lived in this one area for quite some time and only a few months ago did pet-smart finally get a employee that
actually knew about proper care and lighting.
1. You do need a T5 tube light, the ones in the regular fixtures barely give off any UVB.
2. A T5 is perfect for him, and whoever said that is a a straight up lair who definitely does not understand UVB lighting.
By the way I have kept my juvenile underneath a 46" T5 HO Reptisun 10.0 bulb going across her tank and another tank when she was smaller. Only had screen over the basking area and she did perfectly fine with the UVB so close. Which was only about 10-12 inches away from the bottom of the tank.
The
UVB light you have now is most likely not giving off any
UVB light at all because of how weak coil/compacts are and screen blocks out 40-50% of all UVB.
Id go for a 34" Reptisun T5 HO 10.0 UVB Tube light with a fitting reflective fixture. You can get this on amazon for a cheap price.
The reason I say 34" rather than 22" is when you upgrade to the preferred minimum size which is 75 gallons (48"x18"x20") or 120 gallons (4x2x2) you wont have to upgrade the fixture as it will be enough somewhat.
You'll want to mount it right over the basking spot behind or in front of the basking bulb.
The bulb I recommended should be replaced every 6-12 months.
He looks like a healthy little beardie, I do agree he does look just a bit dehydrated but not too much. You can drip water on his nose for
hydration, also make sure you get a new thermometer. Preferably a temp gun as it is the most accurate, if not that then a digital thermometer with a probe. You can get this on amazon.
Basking temps should be 100-110, no lower and no higher.
Warm side (area around the direct basking spot) 88-95.
Cool side 70-85.
Night time temps no lower than 65.
If it drops below this then you need a CHE or ceramic heat emitter which produces no light and only heat. Which by the way beardies can see in color so those red/blue/purple/green lights can not be used during the day or at night.
Make sure you have two supplements to dust his bugs with. One a calcium without d3 and the other a multivitmin. I prefer the Repti-cal brand.
Calcium needs to be dusted 5x a week on at least one meal a day, and multivitmin 2x a week on at least one meal a day.
You need to be feeding him 3x a day, 10-20 healthy staple insects each feeding.
Staple feeders - Crickets, locusts, grasshoppers, silkworms, black soldier fly larvae, dubia roaches, turkish roaches, possibly earthworms.
Treat feeders - Waxworms, hornworms, superworms, mealworms, butterworms.
Wax worms - once a week, 4-5 max.
Hornworms - every other day to every two days, 4-6 max.
Mealworms - every other day to every two days, 5-10 max. Only for beardies above 6 months.
Superworms - once or twice a week, 3-4 max. Only for beardies above 12 months.
Butterworms - once or twice a week, 3-4 max.
Daily greens- Turnip/collard/mustard greens, endive, and kale if added to a mixture of the other staple greens mentioned.
Fruit once or twice a week - Banana, strawberries, blueberries, blackberries, red raspberries.
For more food items -
http://www.thebeardeddragon.org/bearded-dragon-nutrition-data.php#veg
http://www.beautifuldragons.com/Nutrition.html
Although he does look a little dehydrated and you should give him a bit more water. 
