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A Miele dishwasher came with my house and it is still going strong but I have been unsuccessful with cleaning some extremely caked on white hard water/soap residue on the inside and filter parts in the dishwasher. It is almost 1/4 inch thick in some spots.

I have tried soaking parts in white vinegar, calcium-lime-rust remover, dish detergent, nothing seems to budge it. It's as hard as a rock. Is there anything I can use to safely clean these parts?

EDIT: enter image description here enter image description here enter image description here enter image description here

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  • Have you tried mechanical methods?
    – Huesmann
    Dec 18, 2023 at 13:34
  • @huesmann I have tried some strong scrub brushes but that's it. I didn't want to ruin anything. Any suggestions?
    – Markpelly
    Dec 18, 2023 at 13:40
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    How long did you give the solvents to work? It could take many hours or even days to soften that much deposit, and you may need to replace it several times as it is consumed by the reaction.
    – isherwood
    Dec 18, 2023 at 13:54
  • Can you post a photo of what you're describing?
    – Matthew
    Dec 18, 2023 at 15:26
  • Added images above!
    – Markpelly
    Dec 19, 2023 at 1:56

2 Answers 2

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If there is visible scale on the surfaces, there will be just as much in the pipes, filters & sprays etc.

You will probably need a two-fold attack on this.

You need a gel descaler for the visible build-up, then a dedicated washing machine/dishwasher descaler you can run through [probably several] full wash cycles.

I don't know what manufacturers/products you will have access to, but you need products similar to these from Kilrock.
Brush-on Gel - this will adhere better to non-horizontal surfaces than any liquid or spray. It will still need to be left 30 mins, scrubbed, repeat until successful. I use an old toothbrush rather than the fiddly little brush in the cap for larger areas.
In-wash descaler - run through an otherwise empty machine. Again, probably more than one cycle will be required.

No descaler will get rid of ¼" buildup quickly. You might be reapplying every time you walk past the dishwasher for the next week. Patience is required after the long time it's taken to build up.

Does your dishwasher have a built-in water softener?
If it does, it needs maintenance. I was surprised to discover recently that, though they are ubiquitous in British & EU machines, they're rare in the US. Apparently the US is more in favour of whole home softening. See How can I clean this smelly area in my dishwasher? for info on how these work & how to maintain them.

If it doesn't have a softener, then you will have to use your in-wash descaler every month or so… forever. Scale kills washing machines/dishwashers. It also makes them expensive to run, as the scale acts as an insulator on the heating elements.

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  • I looked around and I do not see gel descaler but I did find some on the Jungle website that I can try. Also I do have somewhat hard water but we do NOT have a whole house softener. Apparently, just had to look this up, but in the US we use something called rinse aid which is next to the detergent reservoir. Well I have always skipped this but apparently this is in some ways to help dry dishes but also for softening water a bit. I have read that vinegar could be used in there, there is bad press for the poplar brands of actual rinse aids that is harmful.
    – Markpelly
    Dec 19, 2023 at 2:26
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    Rinse aid doesn't really soften water, it reduces surface tension making it bead up less, so it doesn't leave water spots. It also slightly breaks down calcium. Descaler uses up its active ingredients quite rapidly, so it's not really a case of leaving it on longer [30 mins is enough each time], but refreshing it multiple times. I can now see from the photos the machine is badly neglected with a lot of build up. If you can find an in-wash descaler/cleaner that doesn't require the machine to be run empty, you could just run it in every wash until it's clean, then once a month after that.
    – Tetsujin
    Dec 19, 2023 at 11:26
  • btw, vinegar would work, but it's not good with stainless steel. There are several DIY alternatives, lemon juice, baking soda, borax, though I've never tried any of these. The UK is almost obsessed with keeping things scale-free, so every supermarket has many alternative products, for kettles, steam irons & coffee machines to dishwashers & washing machines.
    – Tetsujin
    Dec 19, 2023 at 11:27
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    Adding vinegar to the rinse aid dispenser, @Markpelly, would dispense vinegar on your dishes as one of the very last steps of the washing process. Many people would then consider the dishes dirty and in need of another wash...
    – FreeMan
    Dec 19, 2023 at 14:03
  • Great points, thank you all.
    – Markpelly
    Dec 20, 2023 at 16:00
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Your description sounds like residues of calcium from hard water. You can get special cleaning agents meant for that, it should say something like decalcifier or similar on the bottle. They work chemically different from regular soap or dishwashing detergent.

Edit: In response to comments, it seems the CLR you mentioned is such a decalcifier. It seems to come as either a spray or a bottle of liquid. For your rather severe case you want to soak the pieces in the liquid. The bottle should have instructions on the details. Just spray and wipe will not be sufficient.

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    While it's not obvious to those unfamiliar with the product, CLR is a specialty product designed for removing Calcium, Lime and Rust. Since the OP's already tried that, this may not help too much. TBH, though, I'd think that a longer soaking in CLR is likely to do the trick.
    – FreeMan
    Dec 18, 2023 at 14:20
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    Please don't denote edits in your answer. Just revise the answer to reflect your current information. All edits are in the revision history anyway.
    – isherwood
    Dec 18, 2023 at 14:32
  • Soaking parts as we speak thank you.
    – Markpelly
    Dec 19, 2023 at 1:58
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    I'm not sure what other damaging ingredients are in CLR, but it quite specifically states not to leave it in contact for more than 2 minutes. clrbrands.com/Products/CLR-Household/… Regular 'descaler only' will use up its active ingredients in about half an hour or so, so it becomes pointless to long-soak, you need to repeat the application.
    – Tetsujin
    Dec 19, 2023 at 16:29

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