Weird Layer on Top of Glycol

[dsmithpdx]

I haven't brewed since April 2022, and I'm getting ready to brew this weekend. I turned off my SS Brewtech glycol chiller after that last brew but left the glycol/water mix in it so it's been sitting in there for about nine months at room temperature. I took the lid off the chiller tonight and saw that there's a layer of something on top of the glycol, and it does look like the top copper coils are perhaps a bit green (see photo). I am using this glycol mixed with distilled water. I don't believe it has an inhibitor in it. Does it look like the glycol has gone bad and needs to be replaced? Or worse, is there any chance I have damaged the chiller?

 

[Wagon_6]

I would replace it just to be safe. If it were to spread, it will be more of a nightmare to try and get it out of coils/lines you cannot see inside.

It’s my understanding that glycol itself is an inhibitor but when it’s at low temperatures. I keep mine set to 27F even when I take a month off from brewing and change out the water/glycol annually. It’s still crystal clear when I go to change it.