Never had this problem before because ALL my pastures but one have spring water tanks. Unhappily, the pasture where my new barn sits has no spring water source. I ran a line from the house to the barn and, of course, had to install a heater in the tank to keep it from freezing in our Wisconsin winters. To my chagrin, I found that on really cold days, the critters would back up to the tank (for the warmth) and then let loose. I found poops floating in the tank almost every morning last winter and had to drain, scrub and refill, which is a LOT of work! Has anyone prevented this from happening by installing some kind of barrier around the tank that would enable the critters to drink but prevent them from backing up close enough to poop? How have YOU addressed this problem?