Originally Posted by Edcculus
Adding campden wont work now. A crushed tablet will treat about 20 gallons of water. I don't feel like measuring less, so I use a tablet for the entire ~8-10 gallons on my brew day. I throw it in when I'm heating the mash or sparge water (1/2 tablet in each).
+1 I do this same thing and it works. This will also work when you water treatment plant switches to Chlorimine. I get 50 tablets for $1.65 so I just use this option and it fixes the issue.
Adding it now will not help you at all, only time I add campden tablets after fermentation is if you are going to add honey or fruit to your beer.