New Hermie Mom, would love advice

[FairyDefender]

So my daughter brought 2 hermit crabs home from school & I didn't realize how much I would like them! She's pretty much lost interest but I've been doing a lot of research & trying my best to spoil them. One was in rough shape, missing it's claw & in a cracked shell! I think we have a good setup now. 25g terrarium, 5-6 inches of sand/coconut substrate, salt & fresh water pools, extra shells from Naples Sea Shells, good food from The Hermit Crab Patch, climbing stuff & even a tiny humidifier. (Not sure how to attach a pic) When offered new shells they both switch within an hour and tried on a few different shells. I even got to see them doing it!! They have been in their new home for a few weeks now. I am worried b/c they are always buried & I don't think they are eating much. I'm pretty sure they are coming up every night. I've seen/heard them a few times and could tell they ate some food once or twice but doesn't seem like much. The temp is good & we have a small moon bulb at night. My concern is if they are preparing to molt how will I know where they are to keep them contained & safe from each other. Also I want to check the moisture of the sand but I don't know where they are so I don't want to dig them up. Plus I'm worried about the inactivity, I want them to be happy & healthy. Any advice on how to handle this would be greatly appreciated.
Sorry for the long post, just trying to give all the details.
I'm so glad to finally find a forum! There is a lot of different and bad care advice out there.

[doth]

I think you are right that they may be preparing to molt! You don't have to separate them as long as they have enough space & deep enough substrate, which it sounds like they do as long as they are not huge crabs.

if the tank's humidity is high enough and the substrate holds its shape (you can clearly see tunnels they dig) then the sub is probably moist enough!

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[FairyDefender]

Thanks for the quick reply!
They're not huge. Kinda hard to describe their size. The shells they chose were the ones with 5/8 openings. I can see some of their tunnels so I guess that means it's good.
I didn't know they wouldn't need to be separated if the substrate was deep enough. I was afraid they might dig each other up. That's a huge relief!

[Hermiesguardian]

Welcome! As doth said, if the substrate is deep enough they should be ok. What can help with that is protein and calcium daily. They do eat very small amounts, hardly noticeable. If they're alive, they're eating. They need total darkness at night and the moon bulb still gives off light. It's ok for viewing but shouldn't be left on all night. They are nocturnal so you probably won't see much daytime action. A lot of us have installed cameras in the tanks so we can see their nighttime antics. Fyi, they are addictive. I started with 2 my daughter brought home from vacation and now have (hopefully) 13.

[curlysister]

Definitely sounds like typical crab behavior! The only time one of my crabs dug up the other, was when I didn't have enough substrate (they had grown and I hadn't kept it deep enough). I have had my crabs for 8 1/2 years. Sonny digs randomly more than Cher, she stays top-side more than him.