I just put in my tank on sunday feb. 11th 3 astoria crabs and two hermit crabs. I noticed a couple days ago that one of the astoria snails was not moving much. Today i decided to investigate and sure enough it was dead. i took it out and noticed a strong smell, not very nice one. I was wondering if a water change will be necessary or if i should let the filter work its magic?Also i have not gotten the protein skimmer yet but i am getting one in 2 weeks.