Removing black marks around bath

[bessie26]

any suggestions on how to get rid of the black marks (mould?) that appear on the sealant around the edge of the bath & in the grouting in-between the bath tiles?

Domestos grot buster. you just put it on and leave it. Miraculous.

cotton wool soaked in bleach then left overnight

dettol mould and mildew remover - just spray it on and leave it to do its magic before wiping away

The only thing thats worked for me is the cotton wool soaked in bleach, have tried all the others!

Thanks ladies, looks like I'm going to have to go buy some bleach!