# What will best dissolve calcuim deposits? **URL:** \ **Category:** Factual Questions\ **Created:** [April 4, 2009, 11:48pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012 "2009-04-04T23:48:44Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Cagey\_Drifter](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@Cagey\_Drifter](https://boards.straightdope.com/u/Cagey_Drifter)\ **Post date:** [April 4, 2009, 11:48pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/1 "2009-04-04T23:48:44Z")
Need help on how to best clean the metal heating surface on a humidifier, which is covered in calcium. But I don’t want to scape the surface. ---
**Author:** ![AuntiePam](https://avatars.discourse-cdn.com/v4/letter/a/f19dbf/32.png) [@AuntiePam](https://boards.straightdope.com/u/AuntiePam)\ **Post date:** [April 4, 2009, 11:51pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/2 "2009-04-04T23:51:07Z")
CLR works like a dream for that. ---
**Author:** ![Cagey\_Drifter](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@Cagey\_Drifter](https://boards.straightdope.com/u/Cagey_Drifter)\ **Post date:** [April 5, 2009, 12:10am UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/3 "2009-04-05T00:10:49Z")
is it safe to breath? It’s the contact surface on a humidifier. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [April 5, 2009, 12:24am UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/4 "2009-04-05T00:24:49Z")
Citric acid will take care of calcium deposits nicely. I use it to clean the stainless steel reservoir of a humidifier monthly. You can buy citric acid at the local food coop, or sometimes in the coffee aisle, where it’s sold as a better alternative to vinegar. ---
**Author:** ![bigcanuknaz](https://avatars.discourse-cdn.com/v4/letter/b/ec9cab/32.png) [@bigcanuknaz](https://boards.straightdope.com/u/bigcanuknaz)\ **Post date:** [April 5, 2009, 12:25am UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/5 "2009-04-05T00:25:04Z")
CLR ingredients are here: > **[Calcium Lime Rust](https://en.wikipedia.org/wiki/Calcium_Lime_Rust)** > > Calcium Lime Rust, more commonly known as CLR, is a household cleaning product used for dissolving stains, such as calcium, lime, and iron oxide deposits. > CLR's ingredients may include various compounds: > One formulation is (by weight) lactic acid 12–18%, gluconic acid 2.50–3.75%, lauramine oxide 1.50–3.25%, with the remainder being water. The product also contained phosphoric acid at one time,\[citation needed\] but it is now phosphate-free. > Weak acids can dissolve calcium deposits and rust with... If you rinse afterward, then none of those ingredients will be a problem. naz ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 5, 2009, 12:49am UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/6 "2009-04-05T00:49:41Z")
> [@](#): > > You can buy citric acid at the local food coop, or sometimes in the coffee aisle, where it’s sold as a better alternative to vinegar. Vinegar will work, too, though. That’s what I usually use to clean calcium deposits. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [April 5, 2009, 2:06am UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/7 "2009-04-05T02:06:26Z")
> [@Chronos](#): > > Vinegar will work, too, though. That’s what I usually use to clean calcium deposits. Yeah. It’s just slower and stinkier. ---
**Author:** ![Cagey\_Drifter](https://avatars.discourse-cdn.com/v4/letter/c/b2d939/32.png) [@Cagey\_Drifter](https://boards.straightdope.com/u/Cagey_Drifter)\ **Post date:** [April 5, 2009, 2:50pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/8 "2009-04-05T14:50:48Z")
thanks, everyone. ---
**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\ **Post date:** [April 5, 2009, 4:07pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/9 "2009-04-05T16:07:15Z")
> [@Squink](#): > > Yeah. It’s just slower and stinkier. Slower maybe, but CLR stinks like dead monkey’s ass and vinegar smells like … vinegar. ---
**Author:** ![Bill\_Door](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@Bill\_Door](https://boards.straightdope.com/u/Bill_Door)\ **Post date:** [April 5, 2009, 4:50pm UTC](https://boards.straightdope.com/t/what-will-best-dissolve-calcuim-deposits/492012/10 "2009-04-05T16:50:04Z")
I usually use 31.5% hydrochloric acid passivated with 126 gallons of Rodine 426 per 1000 gallons of acid diluted to a 5% concentration. That may be overkill for your purposes though. I second the vinegar suggestion. I kind of like the smell, and it’s cheaper than citric acid.