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Descaler for aluminum boilers

edited February 2019 in Have your say
Greetings, my first post .

I have just recently purchased my first gaggia classic coffee machine. It is 16 years old and after reading all the numerous posts online I have managed to replace the pump and set the pressure using a gauge to 9.5 bar.
However after reading that citric acid as a descaler could cause pitting in the aluminium boiler I decided to do some research online for what could be a suitable cleaner.
After some research I have discovered that large scale aluminium boilers used for heating in applications such as schools or offices are treated with organic vegetable based tannin which apparently coats the aluminium preventing pitting and creates a much more effective heating surface.
More research discovers that tannin is contained in green tea or black tea
See ( "")

If others on the forum would like to read the information provided in the above link I would appreciate feedback on whether they think that green or black tea would be a feasible descaling solution.... to be drawn into the Gaga classic aluminium boiler possibly as a descaler but also after descaling with citric acid I could then put a green tea solution through the machine that would coat the aluminium and make it safe from further pitting, improve it's heat exchange abilities and thereby also make it more safe for the consumer in keeping any aluminium compounds out of the coffee.Seems like it could be a simple viable solution.

Ian Morison


  • Wow... welcome and what a great question and first post. These machines are in all honesty not supposed to last forever. That said, they are simple, reliable and effective. Hand on my heart if you use a commercially available espresso machine descaler solution you won’t degrade your boiler or really need to coat the inside with tannins which are prone to leech off the boiler wall pretty quickly I’d imagine in those transient conditions. Now, if the boiler has a leak/weakness and scale is keeping it sealed up, you may cause more issues than you solve. If a machine works without issue tweaking it may only introduce problems that could well be avoided. Feed it good water and coffee for a few months and you may only need a head clean and group seal occasionally. Good luck!
  • This is the reply that I received from the manufacturer of tannin for aluminum boilers TGWT. So your reply was spot on Brett. Quote.... Hello Ian, Thanks for your interest in TGWT. Unfortunately, we are only working in the industrial arena. We do not have household size container. If you just purchased your coffee machine, we can give you the best trick, also applied on the industrial side. You have to get rid of hardness (calcium and magnesium) in the water you are going to poor in your coffee machine. If you get rid of hardness, you will avoid most of the scale. The small amount that will occur will be easily taken out with your citric acid. You can buy small cartridge that you put under your sink that will do the job. If you want to go a little further, you have to keep your pH between 7.0 to 8.0. Do not go over 8.0. By doing that, you should be able to keep it clean. Best Regards, Veronica Martin Inside Sales Coordinator
  • Excellent news mate!
  • I just use a bit of white vinegar  mixed in with my tank water and run it through the machine until I can smell it on the water extracted, then leave it in the machine overnight and do a good flush in the morning! ACG
  • Also I have a 30yr baby Gaggia still going strong it's on 'permanent' loan to a mate now but shows no sign of letting up and is still used daily !

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