I had one also many years ago. I really enjoyed it. I took a piece of glass and siliconed it into the tank, to make a divider of water area and sand/land area.
I had mangroves growing in it and a nice warm and bright light on a timer.
The crabs would warm up and by the middle of the day they were fully energized. They would smack each other around with their claws at times, and you would hear them hitting the glass in the tank.. it was a riot.
Very enjoyable tank and you will surely have a nice time keeping it.