In uk.d-i-y Uncle Al wrote:
Zak wrote:

What is the next strongest mould killer ("mold killer" to the
Americans) I can use?
snip
Kill it with straight chlorine laundry bleach (gloves, goggles,
respirator) and an old toothbrush. Rinse and dry. Apply "Polycell
3-in-1 Mould Killer" and do not rinse. Reapply monthly.

If you had black grout this would't be a problem.

Don't be silly, it's clearly obvious that you'd then get white mould