We had a problem with mold in the bathroom in a rented apartment. The mold was pitch black, hung in the silicone joints as well as in the joints between the tiles, and was not alive and kicking by conventional means. The hardware store has recommended to me to mold destroyer (especially designed for sanitary applications, for the home ranges of mold remover). The high price compared to other funds is justified because Mellerud works beautifully. Applied according to the instructions of the mold was in the tile joints immediately story. But held stubbornly in the silicone. After repeated application over a few days away and leave on overnight and was then eliminated. Mind you: The mold had been for 5 years simply ignored by the previous tenant. In addition, the shower was accessible again, brown calcium deposits disappeared as yellow spots in the joints and on the tiles. One recognizes the shower after treatment hardly. We use it now anyway again without hesitation.