Quote Originally Posted by damha View Post
He said distilled so it is not that.
No, he didn't, he says he's using de-ionized water. They're NOT the same thing; distilled is more suitable than de-ionized because it's cleaner. Looking at the photos I'd say it's the stuff in the water reacting to the copper and separating/building up. Flush the system with hot distilled water, then refill with distilled + silver/PT Nuke -PHN.