HCA: Hermit Crab Association

i got a new crab at the start of the year put her in iso and she went down a few days later, she was down just under a month came up at and drunk alot of water then went back down (i didnt see her during that time) she has been down for another month...should i start to worry...shes not that big...maybe a small.. i got her from petsmart she was the last one left in the tank along with a dead med.

I would give her more time before really starting to worry. Usually shortly after I ask such questions, mine will come up. Are you keeping food and water available in case she is being tricky and coming up when you're not aware?

yes and i smooth out the top so i can tell and shes not coming up.

Also excessive water drinking is also a pre-molt sign as water is stored in a molt sac that assists in exo shed. Correct me if I am wrong.