Black metallic flakes/material in copper counterflow chiller

Wondering if anyone has encountered what I'm experiencing with my new homemade counterflow chiller. After I finished building it I ran boiling vinegar water through it for about ten minutes, then straight water for another ten minutes. About a week later before brew day I ran five gallons of Star San through it into a carboy. After it finished draining into the carboy I noticed a bunch of metallic looking flakes floating in the solution. I dumped the Star San and flushed the cfc with water in both directions for about ten minutes. While flushing the first runnings spat out some very dark stuff that I can only imagine would be the same particulate I found in the carboy that collected the sanitizing solution when I ran out through the cfc. Puzzled, I started over. Ran water both ways and confirmed no metallic looking flakes came out of the chiller. I made a fresh batch of Star San per the manufacturers direction and ran it through the copper chiller. Again it produced the black flakes in the downstream carboy. Could the acid in the sanitizing be reacting with the new copper? Any thoughts?

The Starsan didn't react and create the flakes. It probably loosened existing copper oxide from the inside surfaces, something the plain water wouldn't do. Keep repeating the Starsan flushing cycle until no more debris comes out.

MaxStout said:

The Starsan didn't react and create the flakes. It probably loosened existing copper oxide from the inside surfaces, something the plain water wouldn't do. Keep repeating the Starsan flushing cycle until no more debris comes out.

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+1

Star san really cleans copper up nicely!