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How do I permanently get rid of this discolouration in my bathtub? (I have hard water)
(sh.itjust.works)
I've tried scrubbing it several times with bar keepers friend soft cleanser and although it improves, it never goes away completely and it always comes back.
Almost any store that sells general canning / food preservation supplies will have food grade citric acid crystals. If you're in a part of the world that has Walmart, Target, etc, then those types of places will usually have it. Grocery stores often have it. Sometimes it's considered a seasonal item and is only stocked during times of the year when people are doing lots of canning (i.e. spring through fall).