New crab environment

Hello, I have set up this 10 gallon aquarium for a red clawed, I was wondering if I can put 2 in this environment? Or if there is not enough room for both. I placed an air pump connected to a large ring completely submerged in sand on the left.

And should I add more water? There 2 or 3 inches of water on the right and half an inch the left (small sand hill)