Does anyone else have this problem? I went to go see the horses today and when I busted the ice open there was a big shock. There were about 100 worms crawling in the water. They were regular earthworms...and it's the middle of Winter! I just cleaned it like two days before that. And clean water was put in there. The horses get wormed every other month. The water tank was a large livestock water holder. It holds 200 gallons. Does anyone else's water tanks do this? I closed it off and made the horses drink out of the creek, until I know more...