Pour about a cup of vinegar into the toilet bowl and swish it around with a toilet brush. Let it sit for about a minute. Then add about 1 cup (amount doesn’t need to be exact) of bi carb soda to the toilet bowl and follow it by adding another cup or two of vinegar. Allow about 10 minutes for the fizzing action to work. Use the toilet brush to swish the solution around the bowl making sure to get the solution onto any stains that are above the water line. Don’t flush the toilet. Let the vinegar and soda solution sit a while. Then try scrubbing any remaining stains.