Myster - small clear/white anemones or starfish creatures

Personally I do not believe that a tank treated with copper is a deal breaker and that silicone can not leach levels of copper to such a degree that it will prevent keeping inverts and and corals. Perhaps rock work exposed for longer periods of time or multiple exposures would cause an issue.

I have used tanks treated with copper in the past and did not have an issue if the tank was properly cleaned.

I would take a water sample to the LFS and have them test it for copper. If it test positive looks to using some media that will assist in removing copper and plain old chemipure or other types of carbon.