You generally need a GPH equal or greater than 20x your tanks volume minus the displacement of live rock and sand. Other than that, the choices of wave makers and power heads is pretty large. It really depends on what livestock you plan to keep. Just keep in mind that you don't want any dead spots in your display to give detritus and food/fish waste a chance to settle and give you problems down the road. I always go with a minimum of three or four. One or two to keep the current moving around my tank. One to blow across the back glass for the dead spots you can't see. And one to break up the surface for aeration and gas exchange. I keep the surface looking like it's at a slow boil. If you plan on having a sump, the return pump jets will help with that also. I try to get as much oxygen saturation as possible.