I have 5 hens at this time (a EE, Prod. Red, SLW/BA mix, BO mix, and dom.) Every morning I fill up their waterer, its a 1 gal. It doesn't leak, I've checked the bedding and floor around it... EVERYDAYwhen I get home from school its bone dry. I end up filling it about 3 times a day. The feed store said 10 hens could use it for 2 days! So next week I am geting a new waterer, what size?