High Levels of Iron
I recently posted to an existing thread about these black specks that smear and are hard to clean that show up where hot water exits. Had the plumber come out to take a look and wound up taking a sample from the hot water heater b/c he had never seen this before.
Results show extraordinarily high levels of iron. The plumber suggested that the anode rod may need to be replaced. Does this at all sound right?
I don't know anything about plumbing and the chemistry of water and it's reactions but does a deteriorated anode rod cause this greasy type black stuff?
Other suggestions were the expansion tank and braided connectors, of which both point to disintegrating rubber which apparently didn't come up in the test results of the water.
It is magnesium sulfide caused by a reaction of your water with the magnesium anode rod in your water heater. Replace the anode with an aluminum one.