Yes, we have the same thing... Although the mention of green residue confused me. Our residue is blue, as is the hot water from the taps if you add soap as a catalyst.
Blue will come from coper dissolved in the water, green (if it's proper green) would possibly be more likely to be fe2+... An ion of iron which is green. Fe3+ is orange rust, but is a different ion.
We've had our well water tested, and the pH was between 5 and 6. We've been advised that a changeable neutraliser could be added to harden the water, and that these neutralising agent would need to be changed every so often... A bit like salt blocks in hard water areas.
We've not had ours fitted yet, but this is the right plan:
Central heating system to remain in copper piping, as its a closed system, and will neutralise itself after it eats the first bit of copper.
New water pipe from well in 32mm blue plastic.
All internal water pipe (except heating) to be swapped out for plastic.
Neutraliser unit to be fitted.
HTH