yep, ma H/C is copper/brass and the swiftech is the same
i just make shure that i flush everything out REALLY well before re-assembling my loop
i use a vinegar bath for my blocks.
people say not to use CLR or vinegar for rads but its never hurt me so
my tubes get the same milky build up on the inside but my loop was up for quite a long time (2+yrs), i was running 90% distilled with 10% antifreeze
i threw one of the tubes in a bucket with warm soapy water and it seems to take the stuff off, with help from an old toothbrush