Why do crustaceans always molt when added to my tank?

[happyhourhero]

I added 4 Halloween hermits and a cleaner shrimp to my tank and within 48 hours, all of them molted. I have noticed this before but forgot to ask. Seems to happen particularly when I purchase from a lower quality lfs.

 

[wkscott]

This will happen when the water at the LFS and your tank have really different parameters, especially salinity. If there is a significant difference, you would need to drip acclimate them for seversl hours before adfing to your tank. Did you drip acclimate them?

Shrimp are particularly sensitive and most sea stars would die if not correctly acclimated.