As the topic suggests, I'm taking my old 50' copper immersion chiller coil and repurposing it in my HLT as a HERMS coil.
I noticed when I was cutting the copper tubing that theres a pretty dark oxide layer on the inside walls of the coil where I used to run the cooling water through.
I've read Palmer's Metallurgy section in How To Brew, but am still confused.
1) Should I be concerned about this oxide layer dissolving into my wort?
2) Would pumping some diluted oxy/hot water followed by diluted vinegar / hot water through the coil for a while get rid of any nasties AND this oxide layer?
3) Is there a risk of too much copper getting into my finished beer if the vinegar completely removes the oxide layer, leaving a shiny looking inner tube?
Thanks for your help.