Does carbon bleach your corals ? (Kent carbon recall)

[whatcaneyedo]

A friend provided me his 40 lbs box of Kent Carbon when he shut down a few years ago (2006 maybe?). I didn't use all 40 lbs myself but I did use it exclusively for probably 3 years without issue. However I have heard cases where contaminates like metals have found their way into Carbon and caused coral death. For the last few years I've been using BRS Fine Lignite Carbon because it seemed like a better value.