I have an Urban Coop Company Walk-In Coop that has a built in nipple system for water. At first when they were too small I let them drink from those silver galvanized watering cans. But now that they are bigger they are big enough to drink from nipple system. I removed the silver cans for a few days and everyday when I would let them out and turn on the water hose (like I normally do) they would show a lot of interest in the water...like they are thirsty..like they DONT KNOW how to drink from nipple system or they DONT know its there. I dont see the water level in the tube going down enough....only a few inches which is probably just evaporation. How do I get my chickens and guineas to drink from this nipple watering system?