Yes, yes, yes, yes, yes, please let the guy at the feed store know. Although, it may or may not do any good, at least your conscience will be clear on letting him know. I feel so bad for his poor ducks that he is using bleach on. Oh my God!! Poor things. I just cannot imagine the suffering they are enduring. That is like putting bleach on your upper lip to clean it off. The burining of their nose and lungs must be awful.
I am glad you were able to come here for advice. I have found these forums to be invaluable while raising my ducks. I even read the chicken stuff, although I don't have chickens. LOL
I have learned an incredible amount and feel like a much better duck owner than I would have been without this forum.
Glad you are here. Enjoy your ducks!!
kathy