First thing...change out the crushed walnut shells with newspaper. I know of too many beardies that have died from impaction from ingesting that substrate. Newspaper is cheap and easy to cut to fit, even in tubs.
When I had one beardy, I had him in a 40 gallon breeder tank with natural slate tiles. Of course I had the UV light, CHE, and basking areas. Oh and a custom made temperature controller I made from spare parts at work, maintained the basking area at +/_ 1 degree of setpoint. After I figured out the tiles were hard to keep clean, I switched to newspaper. Then I adopted a mate for him, I had to build a front opening enclosure that was about 5'x2'x2'. That much surface area made me a believer in newspaper and changing out the newspaper every week. Who knew 2 beardies could make such a mess.