Cover the blocked drain with Mentos and Cola
If you did not succeed with the baking powder variant, you can try the following.
Simply unscrew the siphon, place 3-4 Mentos in the drain before the clogged area and screw on the siphon again.
Then, seal the overflow in the sink with a wet rag. Add 1 - 1.5 L of cola to the drain and, at the first sign of reactions in the drain, close it tightly with the stopper (if necessary, hold it tight).
By the pressure the blockage is usually solved. In addition, the Coke dissolved food leftovers in the drain.
