I am thinking about starting a set up for these guys. So, I am thinking a communal set up in a 20 gallon tank with about 4-5 inches of sand topped with an inch or two of peat, with several half logs and such for hides and climbs. About a third of the tank would be a plastic lagoon deep enough to completely submerge a crab, but sloped enough they can easily climb out. Sound ok? A few questions for those who have kept these guys: 1. What would be the best heat source? 2. I have read varying ideas on calcium. Is treating foods with calcium supplement enough, or should I offer cuttlebone? 3. Same on salt water treatment. Should I do it or not? Lagoon should be fresh or salt? Or a seperate salt water source? Am I forgetting anything?