Yes, as the little ones get bigger, they cant submerge their nostrils in those little one qt. or even 1 gal size water fountains. I noticed plug up in my 15 day old Khakis last night--accompanied by some wierd sounds. Now, in add'n. to 1 gall. 'regular' font, i have 1 or two 1/2 rubber bowls in their brooding coop (mess, mess!!!) so that they can DEFINITELY submerge their nostrils if they need to/want to. I am surprised no duck raising book has mentioned this hazard about growing ducklings and their water vessels.