Sodium metabisulphite. How much?

[Brewshed]

I have always used Campden tablets to treat my brewing water (half a tablet for a 21 litre brew). I have now got powdered sodium metabilsuphite instead. Does anyone know how much should I use to replace the half Campden tablet?

Thanks.

 

[Sadfield]

I use 0.015g/L. It's too long ago to remember how I arrived at that figure, possibly 1/4 of a tablet in a 12L batch.

 

[hoppyscotty]

I've used 0.3g per 20 litres in the past which I believe is towards the high end of the suggested band. Don't tend to use it routinely. Have used it in cases where I've had to fill a keg with an open lid rather than a closed transfer and used it once where I was rousing yeast in my fermenter using a blast of Co2, but forgot to purge the line before I opened the valve so pushed air up through the beer, so added some SMB to try to prevent/delay oxidation.

 

[Sadfield]

The OP is asking about water treatment (chlorine/chloromine removal) not oxygen scavenging when packaging.

 

[hoppyscotty]

Gotcha...my bad. If half a tab works then according to Wiki a typical camped tablet contains 0.44g of SMB...so half a tab should equate to around 0.22g.

 

[peebee]

I'll use about 100mg (0.1g) sodium metabisulphite in 50L-ish. At least x2 overkill when I worked it out, but our water company won't add much chlorine (zero chloramine). I do not use Camden tablets.

 

[peebee]

Remarkably there's currently the same subject on the Homebrew Talk forum: https://www.homebrewtalk.com/threads/reading-chlorine-residual-on-water-report.733801/#post-10402570

The mentioning that RO filters do not handle chloramine too well is new on me.

 

[jof]

I got a big pot of sodium metabisulphate.
But I just use a tiny pinch in my strike & sparge water.
If I got it only for beer making, it will probably outlive my brewing career, however I also wash apples in it at the start of my cider making process.

 

[hoppyscotty]

On the basis that one of the uses and properties of SMB is that it is an oxygen scavenger then what is the shelf life of SMB? I've always assumed that once you open the packet and expose it to air then it much go off pretty quick? I've only ever bought it in as small packets as I can assuming that once I open it its no good? surely it cant last indefinitely?

 

[Sadfield]

Keep it dry and in an airtight container it's fine.

 

[MrJay83]

Malt Miller says to use 0.5g for 25 litres of water to remove chlorine