Every summer I give my buckets a good deep cleaning and a full day or so of sun (repeating as needed). They look bright white and then I start to use them again and the inevitable discoloration kicks in...but I don't ferment much in buckets anymore (other than SS Brew Buckets). My buckets hold Iodophor, Star San, BLC mixture, you name it, from time to time...generally I just use them to capture the water from chilling to re-use for cleaning after the wort is racked to fermenter, or earlier in the brew day to weigh out grain bills and catch crushed grain in the underside of my JSP mill. Sometimes I temporarily store extra grain in them, when I stock up in advance of some bigger brew days. They really are handy and stepping up from using them as fermenters doesn't mean that they will not be used!