OK, new input. Isolated problem to the hot water supply line for that shower only. Copper. Acts like the supply line is partly obstructed. Spits out small whitish granules (? mineral deposits) that clog shower head. Do you think the inside of the hot water supply line for that shower is somehow corroded (mineral deposits) and showering pieces of debris through the shower, obstructing the head. How would it get corroded and how do you fix it? Thanks.