Im in need of some help!! I have had my 29gal tank set up for about three months now and have several inverts living in it. Flame Scallop, Emerald Crab, (3) Dwarf Zebra Crabs, (4) Peppermint Shrimp, Coco worm and a tuxedo urchin. All are thriving in the tank. In the last week i have lost three...