What is the volume of your main tank?
-10 gallons(Going to hopefully increase to 55g after a move)
How many hermit crabs do you currently have? How big are they?
-Down to 3(1E 2PP) about 1/4" opening on their shells. The poor guys that passed on were about 7/16" and 1/2" on their shell openings.
How long have you had the hermit crab(s) that you are concerned about?
-All five from about a month ago, the two that died were the two larger ones
What substrate or combination of substrates are you using? How deep is it?
-All Sphagnum moss that states it's safe for reptiles, tropical frogs, hermit crabs, etc. Zoomed brand I think.
What do you feed your hermit crabs?
-Freeze-dried shrimp and various fruits and vegetables.
Do you use distilled, bottled or tap water? If you are using a dechlorinator, what brand is it? Does it state to remove all heavy metals, chlorine and chloramines?
-I'm using tap water, but for now we have well water(until we move)
What brand of sea salt are you using to supply your hermit crabs with salt water?
-Instant Ocean
What heat source are you using and where is it positioned?
-I try to use a Nightglo bulb on an aquarium hood but recently it's gotten a little chillier so I added in an aquarium bulb for some heat temporarily.
Have you calibrated your thermometer(s) and hygrometer?
-Calibrated the, about a year ago when I got them new.
What is the air temperature range and humidity inside the tank? If you are using an under tank heater, what is the temperature range of the substrate (it is likely to be different to the air temperature range)?
-The air temp is about 80 degrees and I try to keep humidity at about 80%
Do you have any photos of your tank or hermit crab(s) of concern? If yes, please attach them to your post.
-Unfortunately no pictures right now, but layout is Water dish, Food dish, Salt Water dish, quite a few shells littered about and a plastic aquarium decorative "Branch" propped up for climbing.
Most of the time they're burrowed down in the moss though, and I can't imagine how humid it is under the moss, it just being lightly damp makes droplets of water form on the sides of the glass though the one that died crawled to a corner and went under and was found dead in that position in that spot
The other made a pocket in the moss and I almost didn't see him.(The three survivors were visible from the bottom glass and were going "
THE GROUND IS A LIE!"
They were new so I wonder if it was stress or if they're actually secretly molting(I've kept them before that were locked in their shells for more than a week with no change, or movement.)
I hate to say it but ohwell, they seem to take MUCH better care for them now than they did when the store opened, to the point this is my only gripe, aside from the painted shell thing but they had some empty natural shells in there too.
I found out that the sand I had been using(Quikrete play sand) wasn't good for them so I switched to the moss.
They're so cute!" so I have the all-clear 
)
keep me posted !!! 
