Ben Z. wrote:I'm not sure the exact chemical reactions, but when you have a few different metals in a bath, strange things can happen. I am almost certain you are seeing the deposition of pure copper (basically electroless plating) on your parts, especially the stainless.

You shouldn't descale different metals together due to the risk of electroplating. Copper is one of the easiest metals to plate something with because it doesn't require any input of electricity. The copper ions from the dissolved copper oxide will plate most metals that are in the same solution.

Also, don't worry about the pink color unless its some sort of build-up. The natural luster of unoxidized copper is pink. We're just used to seeing it with oxidation on it.