Newbie to sw

[Kimmi7]

Ok so I have a question about powerheads. How many do you guys use? I see there are some made for bigger aquariums and they arent badly priced. I was thinking tho that having two one on each end would be good to help with feeding corals better then having one going one way. Correct me if I am wrong. Also I will be having everything under the tank and am honestly thinking of a 120 gallon, 48x24x24. So I am unsure how big of a return pump I would need.