# Chalky White Residue

**URL:** https://community.anovaculinary.com/t/chalky-white-residue/736
**Category:** Anova Precision® Cooker
**Created:** [March 13, 2016, 10:54pm UTC](https://community.anovaculinary.com/t/chalky-white-residue/736 "2016-03-13T22:54:17Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![lordbodom](https://avatars.discourse-cdn.com/v4/letter/l/7feea3/32.png) [@lordbodom](https://community.anovaculinary.com/u/lordbodom)
#### Post date: [March 13, 2016, 10:54pm UTC](https://community.anovaculinary.com/t/chalky-white-residue/736/1 "2016-03-13T22:54:17Z")

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So I cooked some corned beef yesterday in a zip log bag around 170, and after a few hours I could see the water start “foaming” up. after cooking, there was white chalky type sunstance on the machine and around the pot i cooked it in. I dupmped the water from the pot and just left it overnight and this morning i see it covered in this chalk substance. Could this be coming from the ziplock? is it not safe to use a ziplock?

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### Author: ![fischersd](https://sea2.discourse-cdn.com/flex016/user_avatar/community.anovaculinary.com/fischersd/32/5594_2.png) [@fischersd](https://community.anovaculinary.com/u/fischersd)
#### Post date: [March 14, 2016, 1:32am UTC](https://community.anovaculinary.com/t/chalky-white-residue/736/2 "2016-03-14T01:32:22Z")

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Are you using a sandwich bag or a freezer bag? &nbsp;Really not advisable to use a sandwich bag. &nbsp;The material is marginally thicker than cling wrap. &nbsp; You really want to use freezer bags as the plastic is durable enough to be reliable for sous-vide.

  

Also, hard water will leave hard water scale on your container and precision cooker. &nbsp;Get in the habit of cleaning this up after every use (this is where having access to soft water would be highly advisable) 🙂

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### Author: ![lordbodom](https://avatars.discourse-cdn.com/v4/letter/l/7feea3/32.png) [@lordbodom](https://community.anovaculinary.com/u/lordbodom)
#### Post date: [March 14, 2016, 1:42am UTC](https://community.anovaculinary.com/t/chalky-white-residue/736/3 "2016-03-14T01:42:38Z")

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Thanks. Never thought of that. I got ziplock “storage” 1 gallon bags. Guessing those are not the same as freezer bags.

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### Author: ![fischersd](https://sea2.discourse-cdn.com/flex016/user_avatar/community.anovaculinary.com/fischersd/32/5594_2.png) [@fischersd](https://community.anovaculinary.com/u/fischersd)
#### Post date: [March 14, 2016, 3:46pm UTC](https://community.anovaculinary.com/t/chalky-white-residue/736/4 "2016-03-14T15:46:41Z")

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Check the thickness of the plastic on them - they may be fine (but, you really shouldn’t be having any issues with the thicker ziploc bags - I know I don’t). &nbsp;You’re also only using them once, right?&nbsp;

  

Again, I’m buying the freezer bags as I know the plastic is thicker.