There is lots of life in ocean water (plankton) that dies if the water is not oxygenated. So after 2 days you have lots and lots of dead items rotten in the water. You need to either let it set for a few weeks, then only use the clear water on top, or filter it, very very well, or kill it with chlorine, filter and dechlorinate.
sorry seamaiden,typo error, is just for hermit crabs (no 74).
Thanks Kim, I should have known that but thought after plankton etc dies would be Ok. When I 1st put water in tank for hermits they go crazy, prbably love the life in there.
iirc, many crabs eat the muck/sand/mud in their environs, and digest the 'organic soup' therein
they and all the other sand/shore/mud dwellers (burrowing shellfish, etc etc) might be (one of) the reason(s) a huge deep sand bed like a beach, or tidal flat, doesn't stink to high heaven like one would think it should, all things considered
Correct me if I'm wrong, but doesn't the ocean water in these parts of the worls have a much lower salinity level than that of the Peloponnesian area, etc..?
If so, you might want to make sure you check the salinity level before adding tropical critters.