Whirlfloc Tablets are an enhanced blend of Irish Moss and purified carrageenan that aids in the coagulation and settling of haze-producing proteins and beta glucans. Use one tablet per 10 gallon batch (For 5 gallon batches, cut a tablet in half. Adding a whole tablet won’t really gain you anything), and add it with 5 minutes remaining in the boil. Yes, 5 minutes is correct. According to the manufacturer, if Whirlfloc is in the boil for any longer than 10 minutes, the active ingredients become denatured and therefore will not do their job.