I've got a 6 gallon plastic fermenter - one of those food-grade plastic buckets Midwest gives you in the starter kit. I guess after our last brew, my brother and I carelessly tossed the remains of our bag of bottlecaps in there without fully drying out the bucket. Brother just looked in there a few days ago and the caps are all rusty and there are some rust stains in the fermenter.
Obviously we can't use the caps now, but I'm more concerned about the fermenter. My gut tells me that if the stains do not come out with some water and a washrag they probably also won't come out into any beer we ferment in there, but I'm not sure. Should we just get another bucket just to be safe?