If I get a used tank for an octopus, and I clean it really good first, do I still need to worry about whether or not copper was ever used in it??? Or is it safe to assume that if I clean it really well, and dry it out, that it will be ok? Also, I have noticed in a lot of the posts that a lot of you will actually inter-act with your octos, some actually reach in and let the octo touch them. How likely are you to get bitten, or cause the octo to ink?? I'd like to read more about how you "trained" them.