So fill a bucket with very hot water and pour in 1 ½ cups of vinegar and 6/7 drops of essential oil of the perfume you prefer most to obtain a fragrant mixture. Now pour the mixture down the shower drain and let it sit for hours.

citric acid
Like vinegar, citric acid is also able to deodorize and dissolve dirt and limescale. It is also used in the washing machine to remove the hidden dirt.

So simply add 1 tablespoon of citric acid to the shower siphon, leave it to work overnight and turn on the water to clean the next day: the smell is no longer a problem!

Backpulver
Pour 1½ tablespoons of baking soda down the shower drain and leave it overnight. The next day, pour a bucket of hot water down the drain.