Martin,
2 things, I use Clover Chemicals 'Breaker' its brilliant on limescale and 'other'stuff you find in showers and similar things, just squirt, rub down to break things up and rinse it off.
The other thing is, as you have done your trauma course how do you get 'old' blood off walls and floors. A friend of mine is an undertaker and he has asked me if I can clean blood and body fluids off the floor and walls in his treatment room. There isnt much, evidently just splashes etc, the floor is Altro's Safety floor and if I remember correctly a thermo plastic type sheeting to the walls. He has used the usual flash etc etc but to no avail.
Any ideas welcome.
Murky