i'm having a problem with my horse drinking properly. Out in the pasture my horse will drink very well, but when I put him in his stall he won't drink any water. He has been used to his stall for a couple of years now, so it isn't like it's new. We used to have electric waterers, so we couldn't tell how much our horses were drinking. But, our waterers were old, so we replaced them. But it isn't automatic anymore. His bucket of water is always full. Does anyone know why he won't drink?