I was just over in the rabbit forum & someone was suggesting to another poster to put glycerin in hteir rabbits water crocks to keep the water from freezing. My ducks have an electric water dish for winter but it would be nice to give them their swimming pool more often. I was just wondering if glycerin in their pool would hurt them if they drink it which of course they will or affect their feathers at all? Not sure how much glycerin I'd have to use either, For the rabbit crocks the poster suggested 1 tsp. per dish.