Cooler Insulation Beer?

[jlongland]

I recently moved to all grain. My setup is the standard blue Coleman Xtreme 70qt with a stainless steel braid. I went low tech and used a rubber bung, but I might be regretting that now.

I've done two batches and at the end of the boil, I found a blueish-green residue in the bottom of the kettle. Not a lot, but enough to make me wonder what it was. When poking around my cooler tonight, I noticed that the bung allows some insulation into the cooler if the bung is moved too much.

Has anyone come across this? Or is the residue from something else? And most importantly - is the beer still good? I imagine the insulation is toxic?

 

[Bierliebhaber]

I've never come across something like that, but it certainly doesn't sound good.

I know some people use the bungs, but I found it very easy to unscrew the drain valve and reuse the gasket to seal a male threaded coupler. Attack a ball-valve to the outside and another coupler on the inside. I use a manifold so the inside coupler is only threaded on one side.

 

[jlongland]

I'm definitely going to replace the bung. But I'm trying to figure out whether I should dump out my fermenters and get some new batches in there?