Membership questions? Log in issues? Email info@brewersassociation.org

Author Topic: Sodium/Potassium Metabisulfite in the fermenter  (Read 925 times)

Offline KilroyWasHere

  • Cellarman
  • **
  • Posts: 42
  • Lookin' for clues at the scene of the crime
Sodium/Potassium Metabisulfite in the fermenter
« on: May 05, 2024, 08:03:21 am »
Hi all,
I understand the Sodium/Potassium Metabisulfite will 'neutralize' chlorine or chloramine from mash water, but does anyone know if it will do the same for chlorine in the fermenter? If so are there negative effects on flavor, yeast health, ...? Due to my stupidity I ended up with residual chlorine in my Speidel fermenter (cleaned it with bleach) and it leached out into the wort during fermentation. Result was massive cholorphonel and 5 gallons of Belgian Dubbel down the drain $$. I think I've effectively removed the chlorine with soaks of hot (135 F) water and campden tablets, but I'm wondering if a dose of same in the fermenter would be wise as a precautionary measure.
Thanks in advance.
« Last Edit: May 05, 2024, 10:22:14 am by KilroyWasHere »
Beer! No great story ever starts with someone eating a salad.
Being Irish, he had an abiding sense of tragedy to sustain him through temporary periods of joy.

Offline Village Taphouse

  • Brewmaster General
  • *******
  • Posts: 2385
  • Ken from Chicago
    • The new Mayfair Court Brewhouse
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #1 on: May 05, 2024, 09:19:55 am »
 I believe that chlorine will naturally escape off overnight.  If you use a campden tablet or filter the water first, you should not have a problem.  At certain levels, the S/P metabisulfate will  create a 'fart-like' flavor in your beer.  I was using it for O2 control and the low-O2 guys were playing with the amounts .. 100ppm, 50ppm, 25ppm, 12.5ppm .. I could still taste it so I stopped using it.  But getting the chlorine out of your water prior to brewday should be easy.  Just get your volume of water ready the day before you brew and it should gas off.  If that's not handy, a carbon block water filter should work.  I filter all of my water through a water filter either the day before or the day of brewing because my source water smells and tastes like a public pool. 
Ken from Chicago. 
A day without beer is like... just kidding, I have no idea.

Offline KilroyWasHere

  • Cellarman
  • **
  • Posts: 42
  • Lookin' for clues at the scene of the crime
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #2 on: May 05, 2024, 10:14:10 am »
I believe that chlorine will naturally escape off overnight.  If you use a campden tablet or filter the water first, you should not have a problem.  At certain levels, the S/P metabisulfate will  create a 'fart-like' flavor in your beer.  I was using it for O2 control and the low-O2 guys were playing with the amounts .. 100ppm, 50ppm, 25ppm, 12.5ppm .. I could still taste it so I stopped using it.  But getting the chlorine out of your water prior to brewday should be easy.  Just get your volume of water ready the day before you brew and it should gas off.  If that's not handy, a carbon block water filter should work.  I filter all of my water through a water filter either the day before or the day of brewing because my source water smells and tastes like a public pool.


Thanks, the chlorine actually got into the plastic when I foolishly used a bleach solution to clean the fermenter. At the time I thought I might have diastaticus lingering in it, and if that was the case it meant my PBW/Starsan cleaning regiment was not removing it. The brewing water is distilled, no chlor(am)ine.
« Last Edit: May 05, 2024, 10:20:37 am by KilroyWasHere »
Beer! No great story ever starts with someone eating a salad.
Being Irish, he had an abiding sense of tragedy to sustain him through temporary periods of joy.

Offline HopDen

  • Senior Brewmaster
  • ******
  • Posts: 1154
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #3 on: May 05, 2024, 10:34:21 am »
 "fart-like flavor" ..... Please expound on this one!!

Offline Village Taphouse

  • Brewmaster General
  • *******
  • Posts: 2385
  • Ken from Chicago
    • The new Mayfair Court Brewhouse
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #4 on: May 05, 2024, 12:00:04 pm »
"fart-like flavor" ..... Please expound on this one!!
Seriously.  Anyone who was dabbling in low(er)-O2 knows what I'm talking about.  The S/P metabisulfate is a good O2 scavenger and was part of a triple insurance policy against O2 along with BTB and ascorbic acid.  It was supposed to be there for when O2 does creep into your process but at first the level to use was unknown.  I lifted a few glasses of beer to my nose where it smelled like I was drinking straight-up farts.  Heavy sulfur.  Someone mentioned that it would age out but I didn't experience that.  I went down to 12.5ppm and I could still pick it up so I bailed on it.  I'm not spending 4 hours of my time to drink fart beer, no sir.  Imagine serving it to friends!   :o
Ken from Chicago. 
A day without beer is like... just kidding, I have no idea.

Offline Richard

  • Senior Brewmaster
  • ******
  • Posts: 1062
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #5 on: May 05, 2024, 04:50:01 pm »
I believe that chlorine will naturally escape off overnight.  If you use a campden tablet or filter the water first, you should not have a problem.  At certain levels, the S/P metabisulfate will  create a 'fart-like' flavor in your beer.  I was using it for O2 control and the low-O2 guys were playing with the amounts .. 100ppm, 50ppm, 25ppm, 12.5ppm .. I could still taste it so I stopped using it.  But getting the chlorine out of your water prior to brewday should be easy.  Just get your volume of water ready the day before you brew and it should gas off.  If that's not handy, a carbon block water filter should work.  I filter all of my water through a water filter either the day before or the day of brewing because my source water smells and tastes like a public pool.


Thanks, the chlorine actually got into the plastic when I foolishly used a bleach solution to clean the fermenter. At the time I thought I might have diastaticus lingering in it, and if that was the case it meant my PBW/Starsan cleaning regiment was not removing it. The brewing water is distilled, no chlor(am)ine.
That is a reasonable concern, but you should have used iodophor instead of chlorine.
Original Gravity - that would be Newton's

Offline BrewBama

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 6170
Sodium/Potassium Metabisulfite in the fermenter
« Reply #6 on: May 05, 2024, 05:41:18 pm »
"fart-like flavor" ..... Please expound on this one!!
Seriously.  Anyone who was dabbling in low(er)-O2 knows what I'm talking about.  The S/P metabisulfate is a good O2 scavenger and was part of a triple insurance policy against O2 along with BTB and ascorbic acid.  It was supposed to be there for when O2 does creep into your process but at first the level to use was unknown.  I lifted a few glasses of beer to my nose where it smelled like I was drinking straight-up farts.  Heavy sulfur.  Someone mentioned that it would age out but I didn't experience that.  I went down to 12.5ppm and I could still pick it up so I bailed on it.  I'm not spending 4 hours of my time to drink fart beer, no sir.  Imagine serving it to friends!   :o

+1. I was in the same boat and bailed on everything but BtB.

Lately, I have been using ‘OxBlox’ from MoreBeer at .3 grams per gallon strike liquor with really good results. It’s the trifecta blend. I am not sure if I am supposed to but I have been using it in the mash.  I use BtB along with it in the mash and boil.


One day, you’ll wake up and there won’t be anymore time to do the things you’ve always wanted to do. Don’t wait. Do it now.
« Last Edit: May 17, 2024, 01:19:43 pm by BrewBama »

Offline KilroyWasHere

  • Cellarman
  • **
  • Posts: 42
  • Lookin' for clues at the scene of the crime
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #7 on: May 06, 2024, 07:18:04 am »
Thanks all, but the concern is not chlorine in the mash water. It's in the fermenter. I know using a bleach solution to clean the fermenter was a mistake. I am now trying to establish if there is a risk to adding S/P Metabisulfite to the fermenter in an attempt to scavenge any chlorine that leaches out of the plastic during fermentation.
Beer! No great story ever starts with someone eating a salad.
Being Irish, he had an abiding sense of tragedy to sustain him through temporary periods of joy.

Offline mabrungard

  • I spend way too much time on the AHA forum
  • ********
  • Posts: 2911
  • Water matters!
    • Bru'n Water
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #8 on: May 06, 2024, 10:36:37 am »
The reaction between malt components in wort and chlorine compounds is fairly instantaneous. So you won't be able to avoid chlorophenols in the beer by adding metabisulfite after the fact. It's got to be added to the water before that water ever touches the grain.

Now regarding the use of metabisulfite to leave a prophylactic protection against chlorine coming out of plastic, that would be a use that could have merit. Don't over do it though.
Martin B
Carmel, IN

BJCP National
Foam Blowers of Indiana (FBI)

Brewing Water Information at:
https://www.brunwater.com/

Like Bru'n Water on Facebook
https://www.facebook.com/Brun-Water-464551136933908/?ref=bookmarks

Offline KilroyWasHere

  • Cellarman
  • **
  • Posts: 42
  • Lookin' for clues at the scene of the crime
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #9 on: May 06, 2024, 02:35:02 pm »
The reaction between malt components in wort and chlorine compounds is fairly instantaneous. So you won't be able to avoid chlorophenols in the beer by adding metabisulfite after the fact. It's got to be added to the water before that water ever touches the grain.

Now regarding the use of metabisulfite to leave a prophylactic protection against chlorine coming out of plastic, that would be a use that could have merit. Don't over do it though.

Thank you Martin, that answers my question. One follow up if I may.
If the mash contains S/P Metabisulfite but the mash is devoid of chlor(am)ine, would the S/P Meta still be around post boil?
« Last Edit: May 06, 2024, 02:38:04 pm by KilroyWasHere »
Beer! No great story ever starts with someone eating a salad.
Being Irish, he had an abiding sense of tragedy to sustain him through temporary periods of joy.

Offline Skeeter686

  • Assistant Brewer
  • ***
  • Posts: 109
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #10 on: May 15, 2024, 07:31:38 pm »
Seriously.  Anyone who was dabbling in low(er)-O2 knows what I'm talking about.  The S/P metabisulfate is a good O2 scavenger and was part of a triple insurance policy against O2 along with BTB and ascorbic acid.  It was supposed to be there for when O2 does creep into your process but at first the level to use was unknown.  I lifted a few glasses of beer to my nose where it smelled like I was drinking straight-up farts.  Heavy sulfur.  Someone mentioned that it would age out but I didn't experience that.  I went down to 12.5ppm and I could still pick it up so I bailed on it.  I'm not spending 4 hours of my time to drink fart beer, no sir.  Imagine serving it to friends!   :o

So, this was in there for the actual fermentation?  I wonder if the fermentation contributed to the sulfur or something.

I've used the potassium metabisulfate + ascorbic acid when kegging and didn't notice any sulfur, but fermentation was complete by that point.  I'd have to check my notes to figure out the ppm, but I'm sure it was over 12.5.

Offline Village Taphouse

  • Brewmaster General
  • *******
  • Posts: 2385
  • Ken from Chicago
    • The new Mayfair Court Brewhouse
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #11 on: May 16, 2024, 07:47:35 am »
Seriously.  Anyone who was dabbling in low(er)-O2 knows what I'm talking about.  The S/P metabisulfate is a good O2 scavenger and was part of a triple insurance policy against O2 along with BTB and ascorbic acid.  It was supposed to be there for when O2 does creep into your process but at first the level to use was unknown.  I lifted a few glasses of beer to my nose where it smelled like I was drinking straight-up farts.  Heavy sulfur.  Someone mentioned that it would age out but I didn't experience that.  I went down to 12.5ppm and I could still pick it up so I bailed on it.  I'm not spending 4 hours of my time to drink fart beer, no sir.  Imagine serving it to friends!   :o

So, this was in there for the actual fermentation?  I wonder if the fermentation contributed to the sulfur or something.

I've used the potassium metabisulfate + ascorbic acid when kegging and didn't notice any sulfur, but fermentation was complete by that point.  I'd have to check my notes to figure out the ppm, but I'm sure it was over 12.5.
Yes.  The trifecta (BTB, SMB, AA) was added to the mash.  The trick was to find the right amount because if you're too low and you're concerned about O2 pickup, you'll be short.  If you go overboard, you're left with farty beer .. the SMB does not age out or get taken out by the boil or any of that.  The ppm on the SMB was critical and even then you could be in trouble because if the SMB is not expended (because the process was solid enough that there wasn't much O2 in the process to begin with), it would remain and cause this flavor.  The first time it happened the beer was undrinkable.  But even when I thought I got it right, I could still pick it up.  Maybe I'm sensitive to the flavor/aroma.  I stopped using it shortly thereafter. 
Ken from Chicago. 
A day without beer is like... just kidding, I have no idea.

Offline Skeeter686

  • Assistant Brewer
  • ***
  • Posts: 109
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #12 on: May 16, 2024, 04:17:39 pm »
Yes.  The trifecta (BTB, SMB, AA) was added to the mash.  The trick was to find the right amount because if you're too low and you're concerned about O2 pickup, you'll be short.  If you go overboard, you're left with farty beer .. the SMB does not age out or get taken out by the boil or any of that.  The ppm on the SMB was critical and even then you could be in trouble because if the SMB is not expended (because the process was solid enough that there wasn't much O2 in the process to begin with), it would remain and cause this flavor.  The first time it happened the beer was undrinkable.  But even when I thought I got it right, I could still pick it up.  Maybe I'm sensitive to the flavor/aroma.  I stopped using it shortly thereafter.
I guess now I'm going to be looking for it.  Haven't noticed it before, but I've only added it to IPAs, so maybe it's just hiding behind the hops.  I'm sure it would have very little to hide behind in one of your lagers. 🙂

Offline Village Taphouse

  • Brewmaster General
  • *******
  • Posts: 2385
  • Ken from Chicago
    • The new Mayfair Court Brewhouse
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #13 on: May 16, 2024, 09:22:39 pm »
Yes.  The trifecta (BTB, SMB, AA) was added to the mash.  The trick was to find the right amount because if you're too low and you're concerned about O2 pickup, you'll be short.  If you go overboard, you're left with farty beer .. the SMB does not age out or get taken out by the boil or any of that.  The ppm on the SMB was critical and even then you could be in trouble because if the SMB is not expended (because the process was solid enough that there wasn't much O2 in the process to begin with), it would remain and cause this flavor.  The first time it happened the beer was undrinkable.  But even when I thought I got it right, I could still pick it up.  Maybe I'm sensitive to the flavor/aroma.  I stopped using it shortly thereafter.
I guess now I'm going to be looking for it.  Haven't noticed it before, but I've only added it to IPAs, so maybe it's just hiding behind the hops.  I'm sure it would have very little to hide behind in one of your lagers. 🙂
Probably.  Even when I was following the low-O2 stuff, the guys there were trying to find the right amount to use and they admitted that any 'unused' SMB in the beer would produce this flavor so the best bet was to use "just a little less than what you might need" so that there wasn't leftover SMB in the beer. 
Ken from Chicago. 
A day without beer is like... just kidding, I have no idea.

Offline ynotbrusum

  • Official Poobah of No Life. (I Got Ban Hammered by Drew)
  • *********
  • Posts: 4903
Re: Sodium/Potassium Metabisulfite in the fermenter
« Reply #14 on: May 17, 2024, 01:09:23 pm »
I went through the low-ox approach over several years and was making beers with about a gram of KMeta, a gram of Brewtan B and a gram of Ascorbic Acid in a 5 gallon batch in the mash.  I would pre-boil the water and chill to mash temp before adding the water treatment and the grains to dough in with a mash cap (pizza pan that fit the mash tun perfectly with a silicone gasket).  After many, many batches, I pulled out the KMeta and Ascorbic Acid and quit using those.  Then eventually, I let go of the pre-boiling and simply avoided excessive splashing.  The beers seem to turn out fine (I won awards both ways), so I just live with the gentle stirring and modest boil to keep O2 at bay without undertaking more aggressive low O2 measures.  I am not saying that my Helles is just as good as the German brewers or low O2 adherents, but I haven't had one turned down when offered for as long as I can remember.

Just sayin'...KMeta isn't an absolute necessary addition to a good pale lager.
Hodge Garage Brewing: "Brew with a glad heart!"