There is also a second option that you can try. This method is recommended by cleaning experts:
Take an entire tube of toothpaste
Using a needle, make small holes along the entire length of the pipe.
Open the outlet compartment and immerse the pipe where the water is.
At this point, flush the toilet to see what happens. This is a quick and easy way to keep your toilet not only good, but also disinfected and clean. With each pass, the toothpaste is released in small amounts to remove stains and counteract the formation of new stains.