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Thread: Citric acid for descaling

  1. #1
    Join Date
    Feb 2008
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    Default Citric acid for descaling

    Iíve got to descale a tank less hot water heater, pipes are copper. Adding powdered citric acid to water, just not sure of the concentration.

    Thoughts?

  2. #2
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    At work we use 1-2 cups per quart for descaling Jewelry after soldering. 2 cups is pretty strong, so start lower.
    Last edited by lakeside53; 09-13-2019 at 06:35 PM.

  3. #3
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    Nov 2013
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    Hmmm. I descale my dishwasher once a month using about 1/2 cup in around 5 gallons of water per cycle. Think I should increase that?

    -js
    There are no stupid questions. But there are lots of stupid answers. This is the internet.

  4. #4
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    I recently needed to remove about 1/8” thick iron scaling from 4” pipes. We dosed the piping with citric in hot water over night and very little was removed. So we put some of the scale in jars with Hydrochloric, Phosphoric, Citric, and Ascorbic acids all adjusted for a pH of 2.0. Over night only a little dissolved in every acid and the pH was still 2.0. It was then that I realized that you could only remove an amount that would dissolve until it reached saturation. Just like dissolving sugar in water where it reaches saturation and no more will dissolve. Heat helps a lot but not if you let it cool down.

    So we cleaned the pipes with citric at 2.0 pH for two hours each time, drained and refilled 6 times. Pipes were totally clean after that.

  5. #5
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    Quote Originally Posted by Jim Stewart View Post
    Hmmm. I descale my dishwasher once a month using about 1/2 cup in around 5 gallons of water per cycle. Think I should increase that?

    -js
    If it works, no.

  6. #6
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    Atascosa County, Texas
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    WOW! Once a month? And I thought my water was hard. I think I'd be changing washing detergent. I have a two year old stainless steel DW and the inside looks like the day it was installed. I don't do anything except wash dishes in it.

  7. #7
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    Quote Originally Posted by CCWKen View Post
    WOW! Once a month? And I thought my water was hard. I think I'd be changing washing detergent. I have a two year old stainless steel DW and the inside looks like the day it was installed. I don't do anything except wash dishes in it.
    Yeah, that's all I've done since we first installed a dishwasher in the early '70s. I installed this one last spring - because my last one was working perfectly except it got weaker and weaker to the point it wouldn't fully dissolve the detergent in the dispenser.

    A year or two earlier I'd had problems with black specks on the dishes and walls of the machine, called Sears service and got a clown who obviously didn't want to do anything and told me the pump was plugged and the dishwasher had to be replaced. Although our water is very soft (straight from the Sacramento River) it's apparently been carrying increasing amounts of iron sulfide (the black stuff).

    With a bit of research I found that GE recommends citric acid for descaling in their dishwashers so I got some and it made an immediate difference. But eventually the scale in the pump and the spray orifices won the battle. Too bad, I liked that machine.

    So now I have a brand new Maytag with no problems and I plan to run a citric acid rinse once a month as recommended by the company that makes dishwasher cleaner.

    Necessary? Maybe, maybe not. But it's cheap insurance. I buy citric acid in bulk at around $5 a pound.

    -js
    There are no stupid questions. But there are lots of stupid answers. This is the internet.

  8. #8
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    Quote Originally Posted by lakeside53 View Post
    If it works, no.
    Aye, there's the rub. See previous post - if it doesn't work I won't know until it's too late.

    -js
    There are no stupid questions. But there are lots of stupid answers. This is the internet.

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