On Wed, 7 Oct 2020 13:20:41 +0100, The Natural Philosopher wrote:

On 07/10/2020 11:32, tim... wrote:

"The Natural Philosopher" wrote in message
...
On 06/10/2020 15:32, tim... wrote:
My toilet pan has a stain below the watermark that neither bleach nor
readily available acid (vinegar) will remove

what stronger products are easily available that will remove it?



caustic soda

surely the stain that I have is discoloured limescale.

so I need an acid?

well in my experience you will have two things. Limescale and encrusted
fatty turds and turd stains. Acid clears the scale, followed by alkali
to saponify the fats and to bleach the organic stains

Perhaps better to remove the fat first so that the ensuing chemical can get
at the limescale.
I saw in an article somewhere that the main factor in blocking disinfecant
is fat/grease.
--
Peter.
The gods will stay away
whilst religions hold sway