Loose substrate of any kind is dangerous for bearded dragons, if they ingest it it will cause impaction and from this they could die depending on how serious is it. Also What are you bulbs, UBV is what i'm most interested in, do you have one and if you do is it the one pictured? Coil UVB are highly dangerous and you need to get a new bulb asap, repitSUN ten TUBE bulb is the best bulb out there. What do you have to measure your temps.