MB - I was thinking of posting on the same topic (really sad case). There is also similar discoloured calcium deposit under the rims of loos in our house. I have tried Viakal (powerful stuff) to remove it in the past and have even soaked loo paper in Viakal and stuck it to the inflow - but the results weren't brilliant. I remember my father used Spirit of Salts to clean a filthy loo in a house we'd just moved into. I expect you should know what that is and have full protective gear for putting it on!