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Slimey build up???

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Hey everyone, it’s been while since I posted a problem...


So when changing water in my Gaggia Classic I noticed a slimey like film on top of the water (could have been like that for a while but usually just top the water up, this time I removed the tank to was it) so much I cleaned it refitted used for a couple of days, removed the tank again and they layer of film was there again. It looks like the silicone tubes are full of the build up too.


Has anyone else come across anything like this?


the silicon tubing I fitted was sold as food grade so I didn’t think it would be that breaking down, but I’m not sure now?

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I used to find the same with my GC. TBH thought it was just one of those quirks so never investigated. But yes - you’re not the only one.

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It is a common problem particularly if you continually top up rather than remove the tank, wash thoroughly, dry and replace.

The warmth from the boiler holds the water a a nice temperature for mould / slime to multiply (filtered / bottled water has the chlorine removed leaving the water more susceptible to mould growth)

Remove both pipes and lay them in a tray (or stand on end in a bottle) with water and a drop of MILTON in , this will disinfect the pipes.

Empty tank at least once a week and wash the tank.


Garydyke mentioned some stuff for bar brew pipes (Starsan ???) similar stuff

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I agree, this is not unusual. I don't think Gaggia Classic are any more prone than other machines.

It can be accompanied by a slight smell also, in the empty tank, indicating some bacterial or fungal activity. I find a few cleaning uses for Citric Acid crystals (Food Grade) around coffee machines and this is another one.

After a few (2-5) tank refills, it works to find a time to leave the tank and pickup pipes in a citric acid solution for an hour or two and then rinse a couple of times with tap water, before refill.

This seems to keep things fresh for a week or two, or 2-5 tank refills. If you normally just top up the tank, then its best to schedule a regular tank removal and cleaning session.

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