your birds are not getting onto a roof with moss on it, this causes watery eyes and dirty wattles if eaten, they seem to like it for some unknown reason,I would keep them seperated from othe birds, as they could pass on anything through the drinkers or feeders,try some lemon juice on their food,preferably rather than the water,as birds sometimes drink less if the water has something in it they are not used to,and its good for sick birds to drink plenty fresh water,