Whirlfloc is a blend of Irish Moss and purified carrageenan that helps with the precipitation of haze causing proteins and Beta glucans. It is a quick dissolving, highly soluble tablet that is typically added in the last 5 minutes of the boil. One Whirlfloc tablet is appropriate for 10-15 gallons of wort. ECH suggests using half a tablet for 5 gallon batches for most beverages.