[tygo]

When you add a campden tablet to water to eliminate the chloramine what are you adding to the water on a net basis?  Just looking around on the web it looks like adding one campden tablet to 10 gallons of water would add 6.7 ppm sulfur dioxide but that supposedly goes away as it reacts with chlorine and chloramine.  So does that mean that the addition of the tablet adds nothing on a net basis or are there some residual mineral additions that should be taken into account when building your water?

I know that the common convention is that one tablet should be added to 20 gallons of water.  Is there enough of an impact that only half a tablet should be added to 10 gallons? 

[BrewArk]

Municipal water with chloramine added will be above neutral pH, w/mostly monochloramine.  Added sulfur dioxide combines w/water to form some sulfurous acid that reacts w/monochoramine to produce ammonium, chloride, hydrogen, and sulfate ions in your solution.

SO₂ + H₂O --> H₂SO₃,

H₂SO₃ + NH₂Cl + H₂O --> NH₄⁺ + Cl^- + 2H⁺ + SO₄^-

Drinking water is supposed to be less than 4 ppm chloramine, so it looks like you are in the ballpark.

[Jeff Renner]

Extra SO2 won't hurt, and I add some potassium metabisulfite powder (cheaper than campden tabs) to my mash as insurance against oxidation.  It's volatile and is gone by the end of the boil.  Some yeasts, especially lager yeasts, produce SO2, which helps against oxidation in the same way.

[denny]

Extra SO2 won't hurt, and I add some potassium metabisulfite powder (cheaper than campden tabs) to my mash as insurance against oxidation.  It's volatile and is gone by the end of the boil.  Some yeasts, especially lager yeasts, produce SO2, which helps against oxidation in the same way.

Jeff, have you noticed any difference doing that?  I experimented with it fir a year and eventually stopped because I couldn't tell if it was doing anything.  Maybe I wasn't getting enough oxidation to worry about in the first place?

[tygo]

Thanks for the responses.  I'm going to relax and not worry about this, which I figured was the answer but I wanted to confirm.

[tom]

What is the recommended dose to prevent oxidation? I seem to remember 25 ppm, but it is pretty hazy.

[denny]

What is the recommended dose to prevent oxidation? I seem to remember 25 ppm, but it is pretty hazy.

Hazy here, too, Tom.  I recall I'd use either 1/2 or 1 tab in a mash for a 5 gal. batch, but I don't recall what concentration it was.

[Jeff Renner]

Denny - I can't say I've noticed any difference, probably for the same reason that you gave, but it's cheap insurance.  I don't always remember to do it.

I don't know the correct dosage, either, but I use about 1/4 tsp in a ten gallon batch.

[denny]

Jeff, I'm a big fan of cheap insurance!

[ndcube]

How gentle are you guys with your mash (or not gentle).

I'm usually pretty careful but on my first decoction, not so much.  I'll have to see if there is any difference as far as oxidation.

[denny]

Not too gentle.  I pour in water and stir vigorously. 

[Jeff Renner]

I pour in water and stir, but I'm careful not to incorporate air.  Same when I do a decoction - I'm careful not to splash more than a minimum.

[ndcube]

So you think the mash can oxidize in the time it takes to mash?  I would think that the O2 absorbed by any splashing would be driven off in the boil but that's just a WAG.

[Jeff Renner]

This has been a hot and controversial topic over the years among homebrewers.  It has its own acronym, HSA, for hot side aeration.  In theory, at least, if the wort components are oxidized in the mash or any time before chilling, they won't get unoxidized (reduced) later, although the problem may not show up immediately.

If you are a masochist, do a google hbd.org site search for hsa and stand back!

[ndcube]

Don't worry.  I've been there but it's been so long I don't remember most of what I googled.  I just always try to be as careful as possible in case HSA exists.  Just have to get my decoction process down.