Slime, Mold and Pink Residue in an Ice Machine

Commercial ice machines

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Updated October 14, 2026

Quick answer

Slime in an ice machine is biofilm: bacteria and yeast that feed on airborne yeast, sugar and dust drawn in from a kitchen or bar. It shows up as black, pink, orange or brown film in the water trough, on the curtain and in the bin. The fix is a full clean and sanitize per the manufacturer, then a shorter schedule and better air around the machine.

What you are looking at

Color	Usually	Where
Black or dark green	Mold	Bin door seams, curtain, splash areas, drain
Pink or orange	Bacteria or yeast biofilm (often called pink slime)	Water trough, distribution tube, chute
Brown or tan, slimy	Mixed biofilm	Sump, float, water lines
White, hard and gritty	Not slime: mineral scale	Evaporator, trough. See scale

Why it grows

Air. Air-cooled machines pull in large volumes of room air. Near bread proofing, beer taps, dish areas or fryers, that air carries yeast, sugar and grease.
Water and darkness. The sump and chute are damp, dim and room temperature between cycles.
Gaps in cleaning. Areas behind panels and in the chute get missed in a quick wipe-down.
Scale. Rough mineral crust gives biofilm somewhere to hold on.

What the health code expects

The FDA Food Code treats ice as food (Food Code 2022, §1-201.10). Ice bins and the enclosed parts of ice makers must be cleaned at the frequency the manufacturer specifies, or, if there is no specification, often enough to prevent a buildup of soil or mold (§4-602.11(E)(4)). California's Retail Food Code is based on the same principles; your county inspector applies it. Visible slime in a bin or chute is an easy inspection finding. See cleaning, sanitizing and the health code.

How to get rid of it

Empty the bin and discard the ice.
Run the machine's clean cycle with the manufacturer's approved cleaner to remove scale.
Remove the parts the manual says are removable (curtain, distribution tube, trough, sensors) and scrub them in cleaner, then sanitizer.
Sanitize the bin, chute and door.
Run a sanitize cycle and discard the first batch of ice if the manual says so.

Use only the products the manufacturer approves; the wrong chemical can damage plated evaporators and plastic parts. See choosing an ice machine cleaner. If panels must come off or wiring is near, use a professional cleaning service.

Keeping it away

Clean on the manufacturer's interval, and shorten it if slime returns.
Move the machine away from yeast and sugar sources or consider a remote condenser. See cooling types.
Ask about antimicrobial treatment devices (ozone or UV) offered by several manufacturers; they reduce, not replace, cleaning.
Keep the bin door closed and use a dedicated scoop stored outside the ice.

Step-by-step: where to look

Bin door seams and the gasket.
The ice curtain or deflector and its hinge points.
Water trough and distribution tube (inside the food zone).
Sensor lenses and probes.
Dispenser chutes, nozzles and drip trays.
The bin drain and drain pan.

Brand features that help

Manitowoc LuminIce II: optional built-in UV device meant to reduce microbial growth in the food zone.
Indigo NXT access: a hinged front door and front-facing evaporator make the food zone easier to clean.
Scotsman: recommends sanitizing more often than its six-month minimum to reduce illness risk.
Ice-O-Matic: advises more frequent sanitizing in high-yeast environments.

None of these replace a full clean and sanitize.

High-risk settings

Setting	Why slime grows faster
Bars and breweries	Yeast and sugar from beer and mixers
Bakeries and pizza kitchens	Yeast from dough and proofers
Coffee and smoothie shops	Sugar and dairy aerosols
Healthcare dispensers	Damp chutes, constant use

What a technician does

We remove panels, take out the food-zone parts the manual allows, clean and sanitize them and the bin or dispenser, descale, clean the condenser, and look at airflow and location. If slime is returning fast, we suggest a shorter cleaning interval or a treatment device.

Cleaning frequency by setting

Setting	Practical schedule
Low-risk, soft water	Manufacturer's minimum (often every six months)
Bars, bakeries, breweries	Every three to four months, plus weekly bin and chute wipe-downs
Healthcare dispensers	Per facility policy; Follett lists drain pans weekly and full cleaning semi-annually as minimums

Schedules beyond the manufacturer's minimum are practical guidance; the Food Code requires preventing soil and mold buildup.

Step by step: after a slime finding

Stop using the ice and discard what is in the bin.
Clean and sanitize the full food zone and bin per the manual.
Find the source: room air, location, missed parts, or too long between cleanings.
Shorten the schedule and log every cleaning.

Bay Area angle

Hard water and slime feed each other: mineral crust gives biofilm a rough surface to cling to. Machines on harder groundwater-supplied water in the South Bay and Tri-Valley often need shorter cleaning intervals for both reasons. See hard water by area.

When to call a technician

If slime is behind panels, in the evaporator area, or keeps returning within weeks, book a professional clean. A technician can also check air flow and treatment options.

Open 7 days, 8 AM to 5 PM, with emergency service until 9 PM. CA Lic. #776244.

Call 1-800-266-5243 Request service online

Frequently asked questions

Is pink slime in my ice machine dangerous?

It is a sign of microbial growth on a food-contact surface. Stop using the ice, clean and sanitize, and treat it as a food safety issue.

Why does slime come back so fast?

Usually the air around the machine carries yeast and sugar, or parts were missed during cleaning.

Will bleach fix it?

Use only the sanitizer and cleaner your manufacturer approves. Some chemicals damage parts or void guidance.

How often should I clean to prevent mold?

At least as often as the manufacturer specifies, and more often if mold appears. The Food Code requires preventing buildup.

Can I keep using ice while I schedule a cleaning?

If slime is visible on food-contact surfaces, stop using the ice until the machine and bin are cleaned and sanitized.

Related guides

Sources

Published by Cool Aid Air Conditioning & Refrigeration, a family business serving the Bay Area since 1966. Owner Jim McKinny holds California C-20 and C-38 contractor licenses and EPA Universal certification. Repairs we complete carry our 1-year parts & labor warranty.

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