Air pump vs water pump/powerhead

[cichlid]

My questing is regarding a nano reef setup Im planning.

I know, I know, nanos are harder for guys like me who have never done salt, but a friend of mine owns oceanic corals, in aldergrove so I will be dealing with Paul on this one. I do realize they are harder, but Im in this for a challenge.

My question is what is the best route for movement, air pump or water pump? How many GPH movement should I need for a 15 gallon?

[cichlid]

I was thinking about just getting a Fluval U1, and solving both issues, however, they only have a foam insert I want to use a 3 step bio filtration, so Im thinking about just adding something to move water.