Water heater less than 2 years old, plus you changed out your anode rod already. I don't think it's your wh. Well water is notorious for this. Start with a good cleaning of your water softener or have it serviced. How old is your water softener?
What kind of piping do you have?? Also best to start a new thread instead of an old one. You will get better results. Just a suggestion.I have black tar-like specks and they look like tiny pieces of a screen.
They are only in one of my tub when the hot water -not cold— and the other tub is on the other side of the wall. They are tar-like and stick to the tub and smear when trying to clean them. I replaced the hot water tank, but they started again after about 9 months to a year. It has to be in the piping of this one tub— some kind of hose seems to be breaking down.
Hope someone can tell me what it is!!
I have a new tub and don’t want to take a bath in black tar.