I am not convinced small bits of limescale will do a lot of harm on their own. It is the magnetite that grows into ever larger clumps and stick like smelly brown stuff to a blanket.
All things being equal, I would obviously have a system with zero pollutants in it, but as long as I can get the magnetite out, I am happy.
All things being equal, I would obviously have a system with zero pollutants in it, but as long as I can get the magnetite out, I am happy.