Ice Machine Cleaning – Dealing with Scale, Slime, and Mold

Reading Time: 4 minutes Food/Ice Safety, Ice Machine Care

Death and taxes may be the most popular certainties, but for ice machine owners, scale, slime, and sediment are just as inevitable.   We’ll follow up this overview article with a deep dive on each topic with tips on how ice machine cleaning can minimize the buildup of these conditions and get rid of them once they appear.

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Slime and Mold

Slime and mold grab the headlines, so we’ll start there.  Slime and mold form because the ice-making process is exposed to the air around you.  Potable water is chlorinated by your local PUC, so that is rarely the source of contamination.  The air, however, is filled with many contaminants, including mold spores and bacteria.  As water flows over the ice making surface of your ice machine, these contaminants are distributed throughout the ice machine.  Water and other airborne contaminants enable their propagation until you notice the discoloration that comes with a more mature mold.  We’ve evaluated numerous potential customers that have exhibited visible mold in less than 21 days and have designed both preventive ice machine cleaning, treatment and remediation programs to provide their customers with clean and safe ice.


scale, slime and sediment will harm commercial ice machines

Scale build up in dirty ice machine

Scale will form in every ice machine without regular ice machine cleaning.  This is because calcium and magnesium – the ions that form the basis for scale – are in every water source.  Their concentration, measured by hardness, will determine the speed at which scale forms and how frequently you need to clean your machine.  While scale does NOT present a health hazard, it will impact the reliability of your machine as well as it’s longevity.  In the short term valves and numerous small passages can be plugged with scale, thus reducing the production or disabling the machine.  In the long term, scale buildup on the ice making surface (the evaporator) causes a condition called “pitting.”  Pitting is caused by scale adhering so strongly to the evaporator that when it is removed, it tears a microscopic chunk of the evaporator away.  That “pit” is more susceptible to scale adhesion, which causes more damage during cleaning, creating a deeper pit – a cycle which ends with an expensive evaporator replacement or new machine purchase.   The most severe scale condition we have observed was in southeast Ohio, where a brand new machine was “plugged up” by scale in 6 days.  With a dedicated water softener and additional scale prevention techniques, we were able to stabilize the performance of the ice machine.


Sediment is one of the most insidious of the ice machine problems, because it sneaks up on you without many observable characteristics.  Every water source has suspended particles.  Filtration by your PUC manages the particulate count leaving the treatment plant, but a network of pipes – possibly hundreds of miles long – delivers the water to your ice machine.  Some of those pipes may be old which can flake and add particulates to the water source.  Once inside the ice machine, particulates get inside the pump, valves, float switch, etc. and can gum everything up, again rendering your ice machine inoperable.  Dedicated filtration is the obvious first line of defense for reducing particulates in the ice machine, but effective preventive maintenance and ice machine cleaning will ensure that sediment buildup is removed so it can’t cause problems in the long run.


commercial ice machines, sanitation, mold

Given the variability of the factors that cause ice machine problems, it is important to monitor the conditions that give rise to these threats.  A change in menu, a change in water supply sources negotiated by your local PUC, etc. can all have an impact on how your ice machine operates.  Making sure your service provider has some skin in the game for both short term and long term performance of your ice machine is the best way to protect yourself from getting surprised by any of these ice machine problems.


Author’s Qualifications:

As of this posting, we have over 20,000 commercial ice machines under our full-service subscription model. We operate machines in foodservice, industrial, healthcare, hospitality, retail, and office environments.  As the owner and guarantor of the ice machine’s performance, Easy Ice invests significantly in preventive techniques that both extend the life of the machine and ensure is reliable performance.

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