Mike Dobony wrote:
Is it the stuff that surface copper turns into to give it that
classic patina found, for example, on the Statue of Liberty or is it
algae?

Not algae, but patina. These are the main water lines in which the
individual water lines are run from. The individual lines are grey
poly, much like the newer PEX.

Okay, then. You have three practical alternatives:

1. Leave it alone.
2. Polish the pipes, then coat with lacquer to preserve the copper look.
3. Paint the pipes.