Quote Originally Posted by Captain H.N. View Post
No, he didn't, he says he's using de-ionized water. They're NOT the same thing; distilled is more suitable than de-ionized because it's cleaner. Looking at the photos I'd say it's the stuff in the water reacting to the copper and separating/building up. Flush the system with hot distilled water, then refill with distilled + silver/PT Nuke -PHN.
Exactly, I said de-ionized water because I know the difference between de-ionized and distilled.
Distilled water it's better than de-ionized...as you said

I think there is something reacting with copper for sure, and its seems to be the material on these two fittings.
Or maybe the radiator?
The fittings are all from same brand, Aquatuning, and they write they are all brass, nickel plated fittings.

What should I check in the radiator to see if is there something wrong?