Yes, sometimes especially with tank-type systems a reaction can occur with the factory-supplied magnesium anode rod. This emits a hydrogen sulfide or "rotten egg" smell and the typical remedy is to change the rod to an aluminum one and consider sanitizing the tank.

Typically dissolved solids in water stay dissolved and you don't notice them. This is not always the case with hot water, where minerals like calcium and magnesium (often referred to as hardness or scale) like to come out of solution. When this happens, the water dries and a white buildup is noticed (scale)a water test will help determine how much hardness is in the water. Utilizing a salt style water softener or other forms of newer salt-free solutions is a great way to help with this problem.

Typically good pH is identified on a scale between 6.5 and 8.5. Ph that is too low or below 6.5 will be corrosive to metals in your plumbing infrastructure and when that happens the blue-green stains are copper oxidizing out of solution on your fixtures. Correcting the pH by increasing it (using a calcite media) is the best and most common way to correct this issue.