We have hard water in our town too, so the build up is always frustrating. I have tried multiple homemade solutions, plus many store bought varieties, even some that almost made me pass out from the fumes, however nothing has even touched the stains...until now!
Introducing, the hands-down best tub scrub:
Thieves Concentrated Cleaner and Baking Soda!!!
Place 1/4 cup of baking soda in a jar, add concentrated thieves cleaner until you have enough to form a paste.
Grab a scrub brush and wet it and the tub down. Dip in baking soda mixture, and get to scrubbin'!
It took some elbow grease, but the built up scum and mineral deposits came off!!! I was shocked and very, very pleased!
Now! I just need to remember to do it more often so I can prevent future build up!
Happy Oiling,
Mandy