I've read that it's best to stay away from any type of "sandy" substrate for beardies due to a fear of impaction. However, mine tries to dig at the bottom of its tank, so I've been trying to think of something that is similar to sand that won't be harmful if swallowed.
Is there any bearded dragon approved materials to use? I've heard of reptile sand or useing washed play sand, but I was wondering if you could use something like flour or maybe even suger?
You can always make a little dig box for him. As long as he fits comfortably in the box and it fits in the enclosure you can buy vermiculite or even a big bag of mulch. If you do buy the mulch bag you just have to sift out all the bark and stuff and just keep the dirt so it's a little more work, but it works. People use these substances for females to dig when they're laying eggs so it shouldn't be harmful. I'm using vermiculite right now it works pretty awesome
I wouldn't recommend flour or sugar as ultimately they will end up ingesting some of the substrate, Depending on the size of the digging area the safest things to use is probably play sand after washing of course. Keep it far away from food or water. Calci sand i dont recommend only because its what i started with before switching to full ceramic and stone tiles. It is very very dusty , gets everywhere and since its calcium the beardy was bound to ingest it and he did. So it lasted 4 days before remodeling.
If you don't want to put sand or any other substrate directly in your tank, you can also make a dig box. There's a thread around here somewhere that someone used, I think, pure alfalfa pellets or something in the dig box instead of sand and the beardie was perfectly happy. If you don't want to risk the mold of alfalfa or the risk of impaction from sand, another fun alternative is a dig box with scraps of fabric too big for your beardie to eat but still enough to dig through and play in.