It was Paul Alan! He tells me they're still perfect!
Someone did tell him that the copper would corrode and leak, someone else told him the copper would build up with algae. Neither of these things has happened so far. I think the guy who had problems with algae was not covering his tank from the sunlight and the algae was coming from his tank.
He did read something about pure water corroding copper pipes but that was at 42 degrees, I know he only uses an immersion and probably doesn't reach them temps more than a dozen times a year.