Campden Tablet - Desired level ppm of SO2

I bought some campden tablets today manufactured by Crosby & Baker. It states it equates to 30 ppl of SO2 in 1 gallon of water. I feel like that is less than most campden tablets (I'm guessing around 65-75ppm). Can anyone confirm how much I need to use in a 5gal batch?

thx

Batch of what? And for dechlorination or for stabilization?

Shoot for 50-60 ppm per gallon, or roughly 1 normal sized campden tab per gallon.

50ppm*5gal= 250total/30 ppm Crosby tabs= 8.3 crosbys

There is a ton of variabiliy regarding the final ppm of sulfur dioxide, but that is a good estimate.

mbbransc said:

I bought some campden tablets today manufactured by Crosby & Baker. It states it equates to 30 ppl of SO2 in 1 gallon of water. I feel like that is less than most campden tablets (I'm guessing around 65-75ppm). Can anyone confirm how much I need to use in a 5gal batch?

thx

Click to expand...

1 mmol, 222 mg, of potassium metabite is equivalent to 2 mmol, (2*64 = 128 mg) of sulfur dioxide. So 30 ppm in 1 gal (3.785L) is 113.55 mg SO2 which came from 113.55*222/128 = 197 mg metabite. That does seem low. As I recall the typical Campden tablet weighs almost 700 mg and thus contains about 700/222 = 3.15 mmol K2S2O5 which would yield about 403 mg which spread over approximatley 4 L would give about 100 mg/L.

Based on the 700 mg/tablet 1 was enough for 20 gal. See the sticky at https://www.homebrewtalk.com/f128/campden-tablets-sulfites-brewing-water-361073/.