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I cannot recall but I would expect the outlet pipe to be a few inches off the bottom to allow sediment to settle and nut be sucked thought the system.
In the short term I'll continue with my vinegar for the limescale and occasional dose of bleach when the discolouration becomes too much......I'll have a read of the Ecover limescale remover, I'd always assumed it was nothing much more than vinegar!
I am planning new bathrooms so hopefully that will allow us to start out on a more even keel and keep,on top of things.