Do you need a powerhead in a 5 galon nano?

I put a Maxijet 400 in it and the fish were surfing.
It was way to much.
I thought I needed something, but now I am not sure.

I just have 1 large piece of live rock in there for right now.
Would like to add some small coral at some point.

It is a Eclipse 5 gallon corner unit.
The kind with the little Bio-Wheel included.

I just have two firefish and a lawnmower blenny in there.
They seem to be doing fine.
Does it need more waterflow than that?