Pink Slime
Pink slime is a pink or orange bacterial growth caused by Serratia marcescens or Methylobacterium species, commonly seen in hot tubs and pool fittings.
Definition
Pink slime is a pink or orange bacterial growth caused by Serratia marcescens or Methylobacterium species, commonly seen in hot tubs and pool fittings.
Typical Values: Treat with scrubbing + shock; check that sanitiser is reaching all affected areas
In Plain Language
Pink slime is not an algae — it is a bacterial biofilm. It typically appears in wet areas: around hot tub fittings, under cover seals, in tile grout, and around skimmer baskets. It is resistant to normal chlorine levels because it forms a protective slime layer. Treatment requires physical scrubbing to remove the biofilm, followed by shocking the water to 10+ ppm FC.
Why It Matters
Pink slime indicates a biofilm problem that normal maintenance has not addressed. Its presence suggests the sanitiser is not reaching all surfaces effectively.
Typical Values
Treat with scrubbing + shock; check that sanitiser is reaching all affected areas
Last reviewed: 2026-06-01