Can you tell us more about what you are planning on doing with the system?
You will need powerheads in the system for water circulation.
I already run a reef tank so I have just about everything I need including power heads, more live Rock reserved at lfs. Going to run two externals on my new system, I was thinking live rock rubble in the bottom of both then carbon in one and Rowaphos in the other. Does that sound ok.
Canisters won't run media much better. Media like GFO are best run in a reactor.
But with all of that aside, is there a reason you are running phosphate reduction media before knowing if there is a phosphate issue?