I wish someone could locate a formula what the Navy uses.
Most likely Tin based. Not good stuff and is banned world wide for all except commercial shipping
. And even then it is being phased out.
Be cautious about adding things. If you have had results from the peper, then great. But be careful you are not upsetting the balance within the paint. Adding more copper would only result in adding more dollars to your paint. It doesn't take more copper to do the job, just a presence of copper.
However, it's fun experimenting I know. It may be a good idea to read up on what paint is, how it is made and other finer details. This may help you on maintaining a balance. You don't want you paint falling off early and you don't want the surface so ruff that it slows you down and so on.