They are not difficult at all. You could literally raise them in a 5 gallon bucket with the occasional water change.
For better care, slightly warmer temperatures seem to do better (78-ish) -- it at least shortens the time between moulting and speeds up hatching from any berried females, which there will be a lot of. Best way to deliver calcium is in their food. I have a hermit crab pellet food that I use as their staple, and then toss in scraps (leftovers from the other tanks like krill, whitefish, Massivore, etc.) as a treat. For the most part, room temperature and sponge filter will be fine. I give mine lots of hiding spaces (think PVC pipes and elbows) so they don't fight too much. The larger females will injure others. My first and oldest one, Madonna, is in her own separate two gallon tank.
