Clean Yellow Toilet Bowl Stains
Does your toilet bowl look like this after it’s flushed?

The toilet was just flushed. You can see the swirling water. That yellow color is from algae or other organic growth. Stain Solver will clean it. Copyright 2018 Stain Solver Corp
All you have to do to clean the toilet bowl is add some powdered Stain Solver and allow it to start bubbling.
The longer you allow the Stain Solver to work, up to six hours, the less scrubbing you have to do with your toilet brush.

Just add about two tablespoons of Stain Solver to the clear water in the toilet bowl and allow to sit for at least two hours. Copyright 2018 Stain Solver

It’s time to scrub with a normal nylon toilet-bowl brush.

The toilet stains are gone. The small areas that remain require you to use muriatic acid to make the toilet look brand new.