I'm watching some ducks while my friends are out of town. They usually have access to a nice pond, but they are staying in their run while my friends are away. The ducks keep swimming in the heated water troughs and buckets and are getting them absolutely filthy. I'm changing the water twice a day. I bet their water bill will be high. How do I keep the ducks' water clean? My friends never mentioned that this could be an issue, and they're in a dead zone where I can't call to ask. I appreciate any help you guys can give! I don't want to let them down.