HCA: Hermit Crab Association

So I’m wondering how much substrate I should have I have 5 crabs varying from the size of an almond to the size of a golf ball, I was thinking doing a gradual slop might be best to let them pick what dept they enjoy the best, I have what u believe is a 40 gallon tank, not positive but if anyone has any tips on keeping in humidity I’d be greatful my tank didn’t come with a lid and I’ve been using my mother in laws house sign for the top it didn’t go over well

Your substrate should be at least three times as deep as your largest crab. If you do a slope, the shallowest part should be that deep.
I didn't have a lid for my first two tanks - I used saran wrap (plastic wrap) with a corner or two vented for air flow.

Okay I’ll add lots more then and then possibly a second level to accommodate my decorations and climbing stuff I wish I could show you my crabitat, I’ve been keeping a wood piece over the second side of the tank but not the whole thing as I do have a heat lamp and didn’t want it to melt any plastics