How much potassium metabisulfite?

[Morrey]

I have always used 1/2 campden tablet for a 5.5 G batch of beer when treating strike water against potential chloramines or chlorine. I recently ran out of tabs and bought a bag of Potassium Metabisulfite powder, now I need to determine my proper dosage for 7.5G strike water. Thanks.

 

[GilaMinumBeer]

I have always used 1/2 campden tablet for a 5.5 G batch of beer when treating strike water against potential chloramines or chlorine. I recently ran out of tabs and bought a bag of Potassium Metabisulfite powder, now I need to determine my proper dosage for 7.5G strike water. Thanks.

Each tablet has ~.44 gram of metabisulfite. 10 tablets is about one teaspoon.

 

[ajdelange]

That is discussed in the sticky at https://www.homebrewtalk.com/forum/threads/campden-tablets-sulfites-and-brewing-water.361073/

 

[TLaffey]

I have always used 1/2 campden tablet for a 5.5 G batch of beer when treating strike water against potential chloramines or chlorine. I recently ran out of tabs and bought a bag of Potassium Metabisulfite powder, now I need to determine my proper dosage for 7.5G strike water. Thanks.

For quite some time I used 0.8gm of potassium metabisulfite to ~10-11G of strike water. I use a water filter with carbon, but it was leaving some "total chlorine" in the water, which I assumed was chloramine. Based on investigation I've done since, this is more than needed for the chloramine elimination and carried over into the mash/sparge providing some oxidation protection. But I also think it was too much K for yeast health, so if you only have potassium (not sodium) metabisulfite, I'd probably limit use to 300mg in your 7.5G. Based on some numbers I'm using from AJ DeLange, I think that much would neutralize around 3ppm Cl.

 

[ajdelange]

According to the table in the sticky 3 mg/L chloramine would require 9.3 mg/L Kmeta releasing 3.3 mg/L potassium. Surely this level would have no effect on yeast healt. ??

 

[TLaffey]

According to the table in the sticky 3 mg/L chloramine would require 9.3 mg/L Kmeta releasing 3.3 mg/L potassium. Surely this level would have no effect on yeast healt. ??

Agree, 3.3mg/L isn't a problem. Seems I have an error in my calculation, as I come up with ~13mg/L, or about 4x what you have (maybe a missing L/Gal conversion in my spreadsheet?) Thanks.