How do I permanently get rid of this discolouration in my bathtub? (I have hard water)

https://sh.itjust.works/post/19336000

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. close up picture of bathtub floor discolouration [https://sh.itjust.works/pictrs/image/d64d23d8-2e04-49e4-8fb2-8bfc32bba92f.jpeg]

Vinegar

Anything with hard water, just soak with vinegar.

You can even fill a ziplock bag and tie it on a faucet.

If your water is really hard, pour vinegar into that little tube in your toilet too, the jets get clogged easily and that flushes them out and prevents them from blocking up. If they are blocked, the vinegar will eventually open them up if you don’t regularly.

Obviously water softener if you don’t have one, but depending what your waters like you may have to do more.

An alternative to vinegar is citric acid. You can buy it as a tub of crystals so it’s much cheaper because you aren’t paying for water. It’s great because you can add more teaspoons to water to make it stronger than vinegar. Plus it doesn’t smell bad like vinegar.
Where do you find citric acid? I’ve been using white vinegar in a jar in my dishwasher which gets rid of all water spots and cleans better with my hard water. However, I’d like to find a place to purchase citric acid crystals without relying on Amazon.
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).