we have hard water here in Alberta and the mineral stains build up in the toilet bowl and on tubs. When the surfaces to be cleaned are made of porcelain you can carefully scrub the deposits off by wetting the pumice stone and then rubbing it on the mineral build up. Worked like a charm. I read about it first and then tried it. Later I watched a YouTube video on it. Just be careful to not create scratches. How had I not heard of this before? Maybe because I grew up where there was only soft water.
Do you have a favourite cleaning tip? Household or garage?