We have now month old mallard ducklings and we are going through water like something else. We bought a poultry waterer at TSC but its not deep enough to dunk their bills in. Where can I find one appropriate for ducks. Also, they go through about 2 gallons of water a day and its still empty. I fill it up morning and night and its always empty by the time I fill it again. There are 7 of them.