I had my 1 year old god-daughter's b-day party over at my duplex yesterday and my show tank is in the living room where the party spilled into. Well everything went well until I got home today after work and several fish were dead, almost everybug in my sand has surfaced and died, all corals are drooping, all my shrimp are dead, and of those that are not dead they are dying and quick. All my water parameters are absolutely perfect, my temp is 79.5 F, my salinity is 1.025, but there are hollow white floaty things on top of the water (which I believe are the culprit). I think but am not sure that one of my girlfriend's newphews put something in my tank without meaning too, but am not sure. I already did a partial water change 50 percent and it is still looking grim at best. Please anyone at all help and asap. The things on top are all uniform in shape like a miniature white clam shell that is hollow inside and is definitely not from my aquarium. Please help.