The pink or orange film that appears around shower trays and sealant is not mould. It is Serratia marcescens, a bacterium that feeds on soap residue and thrives anywhere that stays damp.

That distinction matters, because mould treatments are designed to kill fungal spores and do very little to a bacterial biofilm. You can bleach it away and watch it return within a fortnight.

Removing it properly

Scrub the film off with a non-abrasive cream cleaner first — the biofilm has to be physically broken before any product can reach what is underneath. Then disinfect, leave for ten minutes, and rinse thoroughly.

Keeping it away

It comes back wherever soap residue and moisture sit together. Rinse the tray after each use, keep the room ventilated for twenty minutes afterwards, and switch from bar soap to a liquid wash if the problem is persistent.