Hittade lite på wetwebmedia "Tramp metals, contaminants brought is accidentally as part of your substrate and aquascaping are a slight possibility with naturally collected materials. Iron, in particular may be a problem, from metal cans, crushing/processing tools, shipping... Be suspicious of 'rust' stains from coral sands, gravel and any volcanic rock." "6) Wipe Out Syndrome I'll mention in passing, in a feeble attempt at comprehensiveness. There are "mysterious" total losses that have been chronicled, especially in newly set-up and monoculture (one species) systems. Bacterial "wars", toxins, and more have been speculated. Suffice it to say/write that there are such things, that you must keep your eyes on your livestocks' behavior, and that if all seems to be going side-ways, 1) check water quality, 2) either execute a massive water change, or 3) move them to your quarantine/hospital/alternate tank." "