I've been using rocks that are about the size of my turtles head if not a little bigger. He seems happy with them. I have to say though that each time I've done a complete clean out of my turtle tank I've been putting less and less rocks in. I started out with about 2 bags of rocks and now I only put in a few handfuls of rocks for him to push around the bottom. When I set up my new tank, I'm planning on getting even large rocks so it's easier to clean.
If you are worried about digging, maybe get some kind of bowl to put in the tank and put rocks in. That might help with the digging urge. I don't know, I'm just guessing.
>>I just recently bought my RES a 40 gallon tank. I have the right setup and they seem to be perfectly happy in their new home. I wanted to put gravel in the tank, but I've been hearing that doing that will make the tank dirtier because of the droppings that settle beneath the gravel, but I've also been heard that RES like to dig. What should I do?
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>>-Janet