I am using Glitz Calcium Scale And Rust Remover to remove the dark stains at the bottom of the toilet bowl.
Yesterday was my first try. I did not remove the standing water. Just pour the solution into the toilet bowl, let it soak for about 7 hours, brushed and flushed. The result was not great. Only 5-10% of the dark stain was removed.
Today is my 2nd try. I scooped out all the standing water completely, poured the undiluted solution into the toilet bowl. About 7 hours later, only 5% of the dark stain has been resolved. See picture.
What should I do next,
add more solution?
Wait longer?
How long is it safe to leave the solution in there without damaging the seal and the pipe?