It was my fault. When I noticed, the toilet in my home had gotten dirty.
When I reformed my house, a merchant explained that this type of toilet was maintenance-free. Everytime after using the toilet, still water flushed over the space to clean it up. However, it did not mean that I did not need to wash the toilet with a brush at all.
The pollution on a toilet composed of urinary stone. It is a crystal made from urine. It looks yellow. And it is hardly come off if you try to rub it off.
Therefore, I sought a detergent.
The detergent for a toilet derives to three categories; Neutral detergent, Chlorine detergent, and Acid detergent.
Neutral detergent is the most common for usual cleaning. It is safe and easy to manipulate. First, I tried one. But it was no use.
Second, I used a chlorine detergent. This kind of materials makes toxic gas. So I had to be careful. After dripping the liquid on the toilet, I kept it for a while. The pollution got better a little, although it still needed more improvement.
At last I decided to introduce an acid type detergent. This liquid is similar to hydrochloric acid. Thus I was extremely nervous to deal with it.
The result was satisfactory.
Acid detergent neutralizes the urinary stone with acid-base reaction. After repeated cleaning, my toilet got clean again.
By the way, you never mix acid detergent and chlorine one. It is terribly dangerous.
House cleaning is usual matter, and so quite important.