"Pink slime" is a common bacteria (often Serratia marcescens) that loves damp environments. This indicates the humidifier needs to be cleaned more frequently. We recommend cleaning the tank and lid with warm soapy water every three (3) days and doing a vinegar soak every 2-4 weeks. Do not fill water into the mist tube to avoid damage.
It is not specific to Glow—it can happen in any humidifier, shower, or sink.