From what I have read here and other places it doesn't hurt anything to leave it in the tank. You can remove it if you wish. I personally just leave mine.
thanks...I usually remove them after a couple of days when I figure the crabs new shell has hardened. I know they leave them out to fool potential predators but my sally molted and the shell is in a difficult place in the rocks to get at so I wasn't sure.
Well, they are inert as far as water is concerned, but they do break down very, very slowly to bacterial action. Certainly not enough to ever cause any sort of nutrient spike, etc.
i leave my molts in the tank as well. usually something will munch on it, like the hermits themselves, the blood shrimp, or the star. i've neer noticed a spike post-molt, so i just leave them be. they're usually gone in about a week's time anyhow.