I don't know if this is a bug or a feature, so i came here and in the suggestions page too.
Bubble columns make bubbles only they have above them water source blocks, the problem comes when you make something with a bubble column on land. It's really frustrating to put a source block one by one. Can you make flowing water blocks work with bubble columns?A player can't make a bubble column elevator because if he want it to work he need to put a source block one by one.
Sorry (again) for my english.
It's in fact a feature request.