# Water Aeration



## UsernameTaken (21/6/17)

This could be my stupidest question yet so look out!

When i'm filling my urn on brew day to mash and boil as I do in the single vessel. Should I be careful not to overly aerate the water or does it not matter before the gran hit's it?

Cheers,
UNT


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## Lionman (21/6/17)

It doesnt matter until after fermentation.


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## Dae Tripper (21/6/17)

Well you want to aerate the wort for the yeast. 
Anyway you won't have any problems with it in your urn.


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## GalBrew (21/6/17)

That is a matter of opinion, there are plenty of people doing everything they can to minimise oxygen pickup in the brew house including adding metabisulfite to their water. Look up then LODO threds. At the very least it's an interesting read. Personally I would try to avoid aerating the water as best I could without going overboard.


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## UsernameTaken (21/6/17)

I have been filling my urn with pretty high pressure from the garden hose to get it done quickly and then pre-boiling it the night before brew day.

It's usually around 40c the next morning and takes no time to get up to 72 or so to mash in!


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## Lionman (22/6/17)

Heating the water pushes pretty much all the disolved gasses out of solution. A liquids propensity to absorb gas is related to its temp. The hotter it is, the less gas it will retain.

Coupled with the fact yeast needed DO in the wort at pitch, there is no need to worry about it until after fermentation. 

Before this point the wort is usually hot and so has pretty much no DO. 

At pitch the yeast will consume all the DO. 

It's only after/during fermentation DO is a worry, unless your storing unfermented wort at room temperature or cooler for any length of time prior to pitching yeast, in which case DO is probably the least of your worries.


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## pnorkle (22/6/17)

Lionman said:


> Heating the water pushes pretty much all the disolved gasses out of solution. A liquids propensity to absorb gas is related to its temp. The hotter it is, the less gas it will retain.
> 
> Coupled with the fact yeast needed DO in the wort at pitch, there is no need to worry about it until after fermentation.
> 
> ...


Never heard of HSA?


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## MHB (22/6/17)

Lionman said:


> It doesnt matter until after fermentation.





Lionman said:


> Heating the water pushes pretty much all the disolved gasses out of solution. A liquids propensity to absorb gas is related to its temp. The hotter it is, the less gas it will retain.
> Coupled with the fact yeast needed DO in the wort at pitch, there is no need to worry about it until after fermentation.
> Before this point the wort is usually hot and so has pretty much no DO.
> At pitch the yeast will consume all the DO.
> It's only after/during fermentation DO is a worry, unless your storing unfermented wort at room temperature or cooler for any length of time prior to pitching yeast, in which case DO is probably the least of your worries.



As mentioned above HSA is real and clearly occurs before fermentation, although you are right in saying that the amount of dissolved DO goes down as temperature goes up, the rate of reaction also goes up with temperature, so less oxygen will do more harm faster in a hotter environment!
I think GalBrew is making a lot more sense, there are lots of flavour effects more damaging than HSA, that said it makes sense to minimise a known harm, rather than just "pretend" it isn't there.
The other related one being Chlorine/Chloramine, simply tossing a pinch of Metabisulphite or a Campden tablet into your water at the start will fix both at the same time.
Mark


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## RobW (22/6/17)

My standard practice is to boil the water the night before then cool overnight and add metabisulphite just before mash in.
That seems to be a simple way to address most of the issues raised here without going to extremes to reduce DO.


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## Lionman (22/6/17)

I have heard of HSA but I'm not convinced its an issue for home brewers, especially if you are using typical modern home brewing techniques.

If you LODO for the enjoyment of process refinement or for a particular recipe etc then thats cool, but I dont think its up there with the important factors of producing quality home brew.


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## Danscraftbeer (22/6/17)

I cant quote any scientific evidence but there is a theory of anti oxidant use in the mash. As a means to neutralise hot side aeration. Like 2-5g Cinnamon stick crushed and in with the mash. I do this because its natural ingredient and so small you get no cinnamon flavour after all the mash/boil/ferment process, and its not chemical so to speak. Maybe paranoia but that Sodium Metabisulphite offends my senses. God awful stinky stuff but then again when dosages are so tiny it wont flavour follow through.

What are the dosages of say Campden Tablets? Sodium Metabisulphide? I have them but never used it, yet.


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