How do you keep it from becoming a green algae filled mess?how big is your flock? I have 10 chickens, that 30 gallon barrel lasts two weeks. and it takes less than 10 minutes to fill it, no standing around waiting on it. I start the hose and let it run while I'm doing other chores around the coop, cleaning the poop tray, filling the feeder, knocking down wasp nests etc. My coop is just a few steps from the garden, I can start the water and go pull a few weeds to throw in the run while it's filling. It's not like its a big deal to wait a few minutes to fill a water barrel, LOL
as for the hens teaching them, well, yeah they would so make sure to put some at different heights for sure, but, I used nipples on coke bottles in my brooder and they took right to them within minutes. Not hard for them to learn to use them at all. I didn't actually like the coke bottles though, without some kind of vent hole, they don't work that well. I eventually just went with a small bucket for the brooder.