Does he still drink enough when it is partly buried? Mine gives up if there is anything in it.

Does hemp hold up in the pee corner the same way? Paper falls apart for me there within a day.

I mix both. Paper on top for softness, hemp underneath for structure. Best of both.

What sand are you using? I have been nervous about dust.

Mine was the same at 10%. It was 30% mixed with his old food that finally got him eating them.

Fifteen centimetres across the whole base is the safe answer, but honestly if he is burrowing and not barbering, he is probably fine.

Mine did exactly the same until I made one corner 25cm and left the rest at about 10. He ignored the shallow half completely.