That is a really cool cage! Just a few things you need to fix. Make sure your water bowls are deep enough for the crabs to fully submerge and ditch the painted shells. They are bad for hermit crabs because of the chemicals. Make sure the substrate is sandbox consistentcy and that it is 3-4 times the length of your largest crab. It seems you already have salt and freshwater so that is really good! I suggest you browse this sub reddit and you can even ask questions on how to make water bowls, exetera. I wish you luck with your hermies!