# Descaling GC 2019 Pro - black water and particulates



## RMcG (Dec 21, 2019)

I descaled my gaggia classic 2019 this evening using Durgol because I read that it was better for aluminium boilers. First time descale, been using the machine from new for about 6 months with filtered tap water.

I ran the durgol solution through the machine once and then let it sit for 20 mins. When I came back and ran the rest of through the water that came out was quite dark and had black particulates in it. It was discoloured from both the group head and steam wand. It also stank like nothing else, almost a rotten eggs type of smell. After flushing some more clean water through it ran clear again. I continued to run more clean water through it and it stayed clear.

So, is it worth me taking apart the boiler and looking inside? Has anyone else had a similar issue with this machine? Is this normal and I'm just worrying over nothing?


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## shodjoe1 (Apr 25, 2018)

I would suggest to use only gaggia decalcificante.


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## allikat (Jan 27, 2020)

Assuming that you used the "Durgol Swiss Espresso" descaler ( https://www.durgol.com/int/products/durgol-swiss-espresso/ ), that contains sulfamic acid. The eggy smell would be from the sulphur in the compound.

The question here, is what reacted with the descaler to liberate the sulphur?

I recently descaled a nearly 20 year old gaggia boiler with citric acid, and didn't get anything like that. Perhaps next time try the Puly descaler?


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## RMcG (Dec 21, 2019)

I took the boiler off in the end to have a nosy. Never again, that was an absolute pain! On videos for older model GCs it appears you can just unclip the two hoses that go into the bottom the boiler (solenoid and water-in I guess?). The clips don't come off on the new GC, or at least I couldn't find a way anyway, so I had to unbolt the connectors at the bottom with the boiler still in place.

There was a grey slime on the inside of the boiler, which with a bit of scrubbing came off pretty easily.

I guess the jury's still out on what descaler to use - I chose durgol because lots of people say that citric acid based descalers (like the gaggia descaler seems to be) shouldn't be used on aluminium boilers. Next time I descale I definitely won't leave the stuff in for as long...


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## MediumRoastSteam (Jul 7, 2015)

Had a Classic for 3 years back in 2011. Citric acid is the way forward. I used Pully back then.


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## L&R (Mar 8, 2018)

Alu boiler will become dark again in a week or so. This patina stops the water to react with aluminum further. Lucky you didn't break the clamps they are one time usable.


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## RMcG (Dec 21, 2019)

L&R said:


> Lucky you didn't break the clamps they are one time usable.


 Good to know about the clamps for future reference. I was close to some heavy handed plier action with them - I'm glad I didn't get too angry!


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## shodjoe1 (Apr 25, 2018)

RMcG said:


> I took the boiler off in the end to have a nosy. Never again, that was an absolute pain! On videos for older model GCs it appears you can just unclip the two hoses that go into the bottom the boiler (solenoid and water-in I guess?). The clips don't come off on the new GC, or at least I couldn't find a way anyway, so I had to unbolt the connectors at the bottom with the boiler still in place.
> 
> There was a grey slime on the inside of the boiler, which with a bit of scrubbing came off pretty easily.
> 
> ...


 Gaggia decalcificante is made for descaling aluminium boilers!.It contains <25% Citric acid,<10% I-(+)- lactic acid and Corrosion inhibitor which is a chemical compound added to liquid or gas decreases the corrosion rate of a material!I think comrades in Italy having good knowledge in chemistry and mixing very nice elixir which works like a charm 😄


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## Ademuk (Nov 11, 2020)

Was there any concessus on this?

This happened to me the I first time I descaled my new Gaggia Classic 2019 with Durgol. I used 1:1 ratio as per Durgol instructions.

Is it damaging to the Gaggia?

What is the grey slime?


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## Stox (Jul 19, 2020)

Gaggia Decalcificante (which is lactic acid based) is the recommended stuff, and I'm not convinced that Durgol is an appropriate equivalent.

I think a lot depends on how clean things are kept in day to day use. Also, do you backflush regularly? Gaggia don't recommend this (as in, don't even mention the possibility) in the 2019 Classic manual. It's possible some of what you're seeing is crud dislodged from the group head/shower screen rather than from the boiler.

I live in a hard water area and the regime is:

- Filtered water into the tank plus an in-tank filter

- Quick flush and group-head wipe after each shot to clear anything left on the shower screen.

- Longer cooling flush after steaming before switching the machine off.

- Backflush every now and then with Cafiza (say 1 or 2 times/week)

- Descale with Gaggia Decalcificante roughly once/month

Everything comes out nice and clean every time.

I will probably move to a cheaper lactic acid based descaler when I run out of the Gaggia stuff. e.g.

https://www.descaler.co.uk/articles/difference-lactic-citric-acid/

https://www.descaler.co.uk/eccellente-lactic-descaler-500ml/


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## Ademuk (Nov 11, 2020)

Thanks for your reply Stox,

I backflush every 2/3 weeks with a small amount of Cafiza, and only use filtered water when filling tank.

The dark water that came out after 15/20 of letting Durgol soak, it was almost black and smelt like rotten egg (exactly as original op described).

I used 1:1 Durgol water mix as recommended by Durgol. I'm wondering whether this mix was not diluted enough and I should instead fill the remainder of the tank with water next time.

I will however take your advice and look at Gaggia Decalcificante next time..


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## Sprigpod (11 mo ago)

Ademuk said:


> Was there any concessus on this?
> 
> This happened to me the I first time I descaled my new Gaggia Classic 2019 with Durgol. I used 1:1 ratio as per Durgol instructions.
> 
> ...


Late to the party....Just had the same issue with my new Gaggia, I don't want to take the boiler apart, what do you use now to descale?


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