Over the couse of the past month and a half I have lost three margarita snails and today I came home and found my emerald crab dead. Each time the same thing happens, i check the tank in the morning and they're all moving around eating algae and that evening they're upside down and dead. I checked my water parameters and everything is ok (alk, nitrite, ammonia, nitrate), and the rest of my livestock, which consists of 5 reef hermits, 4 other margarita snails, a scooter blenny, and a bunch of copepods and peanut worms, is all doing fine. Does anyone have any ideas? ???