I can sympathize with you on this one - sometimes, my crabs just bury themselves. I think that your assessment of their feelings about the shell grit, though, are a little bit off. Typically, when you get new hermit crabs, they need to destress - and the easiest way to do this is to bury themselves and calm down, essentially, then come back up. A lot of hermit crabs also need to molt, which oftentimes also involves burying themselves. While you say that your crabs loved the shell grit and were active when you had it, I am not sure this is the case. I think that they were so active because they were trying to find a place to go to bury themselves, destress, and molt if possible. I think they were frantically looking for somewhere to chill out for a little while.
Now that you've switched to sand and they're buried, leave it this way - if your crabs have buried to destress, this is HIGHLY beneficial to them - it will help them to live longer and happier lives. While they are buried now, they will most likely come out in the future - I have a crab that I've had since September that I've actually been able to play with just this month because he was always buried. He's since had two molts, has grown quite a bit, and finally loves to play.
There are quite a few reasons that crabs bury themselves. The first is that something in the tank isn't right - it's too hot, too cold, they're exposed to something that irritates them (perfumes, scented candles, scented lotions, pine wood, etc.), they're bored, they're destressing, they're going to molt, or they just enjoy digging. Without getting a full description of your tank, I can't say for sure which it is, but I can say this - if your crab is burying, it is most likely because he or she needs to. By choosing hermit crabs as a pet, we are accepting that they make the decisions. They aren't really trainable like a dog, and sometimes they just want to dig and there's nothing we can do about it without the risk of killing them.
I also can't speak as to the safety of "shell grit" as a substrate - I've never heard of it. Do you have a link to the product? Also, if you have six crabs, a single ice cream container most likely won't be enough room if all six decide to molt simultaneously (quite a few people have seen mass molts like that occur) or even just want to dig. Of my six crabs, I only see two daily - I see the other ones on occasion. Then again, I just switched them to a new tank a month ago with a new kind of sand, so they need time to destress and just get used to the new stuff. I think if you make that "molting corner" you will most likely be disappointed as most or all of your crabs will most likely end up digging in it. My advice is to give them a few months (my smallest crabs molt in around a month, but they destressed for two before that) and see if they aren't more active. It isn't fun when they're not active, but it's really for the best. Be patient, and look forward to when they come up, not stressed, and can be played with.
Follow the daily lives of my crabs at thedailyhermit.tumblr.com
Rack, 23 Sep 08; Benny, 23 Sep 08; Slightly, 3 Jan 09; Nibs, 3 Jan 09; Curly, 3 Jan 09; Spaz, 5 Jul 09If you are contacted privately and enticed to join another forum, please inform a moderator. This is an unethical practice.