I'm sure I saw a thread on this here recently but I can't find it. Anyway our downstairs loo has dark (it's stained limescale) deposit in the bowl, and a yellow stain around the rim - above the place where you squirt the stuff under the rim, it's all along the rim itself.
This toilet is the worst one as my DS uses it before going to school, forgets to flush in his eagerness to save the planet, and the wee sits there all day.
Any hints you could pass on to me?