+1 to Dallas
I also use 306's, but I have marineland 450's running. They come with a whole bunch of parts for different configurations. I use the parts (a bit lesser flow) that allow me to attach a plastic bottle. I fill with floss for extra mech. filtering. Kinda like a two bangs for the buck.
I do have a aqueon 950 powerhead, no adapters just straight powerhead. It is way too strong for my tanks, even the africans don't like it. I must have tried a hundred positions, in two different tanks.
Alot depends on the fish you have and can be researched. I have some rosey barbs that love to chase 'upstream', but they are with tetras that completely avoid it.......