Power heads?

Hello,
I'm going to buy powerheads for my biocube hqi. I like the koralia nano powerheads, but I'm not sure exactly which models to go with. How much water movement is enough without making the current too strong? If I go with 2 of the smaller 240 pumps, including my water pump ill be at 720 gph. I would step it up with the bigger 425 powerheads, but Im afraid these would create current that would be too strong. These powerheads also work with an inexpensive wave maker.
Any advice would be greatly appriciated, is a wavemaker a good thing to have?

I would think two of the smaller ones would be fine, and random flow made a huge difference in my tank