HCA: Hermit Crab Association

So I have noticed a few over wet patches at the bottom of my sub and want to add sand to the bottom of the tank. However I have a molter down. (I only have 2 crabbys) I think I know where the molter is under, and I don't want to leave those wet patches (caused by a crab digging under the water dish causing a huge spill!) to cause a bacterial bloom! Best practices for adding sand with a molter? And for getting the fresh sand all the way to the bottom? Thanks for any advice!

Uncompressed cocofiber or a roll of paper towels jammed down a small hole would do a better job with soaking up any standing water. Only way to get dry sand down there would be to mix it up which could disturb your molter.