Hi - while performing a partial water change to my 6-gallon tank, I forgot to unplug my water heater, so it cracked when exposed to the air. I did not realize this until 3 hrs later. When I realized it, there was a smoky, electrical smell in the water and the coral that I had looked "limp" and not vibrant. I went to my local fish store and they told me everything would be fine. that my filtration system (carbon filter) would filter the odor out and that the coral is sensitive and that it would look limp on any partial water changes due to stress. He told me to give the coral 2-3 days to pep up again. Is all this true and how will I know if the coral is dead and not just "limp"? THANKS!