This kind of water tank is good for placing stones.
It is better to put stones in the turtle, because it excretes frequently and there are some food residues, so the water needs to be cleaned every day. If you put sand, it will be very difficult to clean.
Putting stones in the turtle tank can also increase its decorativeness and make the turtle's environment look more natural and beautiful. At the same time, stones generally do not absorb water, so they are easier to clean and less likely to breed bacteria.