The blackening of the water in the aluminum pot is mainly due to the chemical reaction between the iron salt contained in the water and aluminum during the heating process, resulting in the replacement of ferric oxide. It is black and will adhere to the aluminum pot. Generally, it can be removed with acidic substances, but it can not be removed if you don't mind too much. Therefore, it will be produced when boiling water next time.
Many friends feel very strange when using an aluminum pot to boil water. Why does it turn black after not using it for several times? In fact, this is mainly because the water contains a small amount of iron salt, which has a displacement reaction with aluminum during heating. The replaced ferric oxide is black and will adhere to the aluminum pot.
Therefore, generally, after the aluminum pot has finished burning water, all the places where it encounters water will turn black, mainly for this reason, but we don't have to worry too much. It doesn't do much harm to people's body, and we can dissolve it with common vinegar, lemon and other acidic substances to restore the brightness of the aluminum pot.
However, if you don't mind, you don't have to remove the black material attached to the aluminum pot, because it will still turn black as long as you boil water again after removal. If you remove it every time, it will make the aluminum wall thinner and affect the use time.