Copper Removal?
 

I have an empty 50 gallon tank that would make a fine reef tank.

I got it from a guy that used it to winter his pond fish (gold fish I believe).

Anyway, it badly needs to be re-sealed.

Once the old silicone is removed, the glass cleaned with acetone and the new silicone is applied, do I need to worry about copper traces?

Should be fine, just give it a good clean with vinegar.