"nuclear option" for mold growth on ceramics and other tiles?
Anytime I get any mold growing in a very humid area, like areas around a shower I spray the mold growth with a strong water/bleach mixture (about 4 to 1) water to bleach. let it sit and the mold goes away. If it is a heavy growth you may need to spray it twice. And yes, wear protective clothing and a respirator.