It depends on the kind of wave maker you get as to weather or not you will need powerheads.
If you get an electronic wave maker, which turns on and off powerheads then you will also need powerheads.
If you get a SCWD, you can install it in the retrun to the tank in most cases.
Or their is a new wavemaker (which I am dying to get some feed back on) which will suck in several gallons of water and push it back out.
I am currenly using the SCWD and very happy with it. However I did have to run extremly small diameter line back to the tank in order to get the push I wanted coming out of the return pipe (this is something that is prob. specific to my application). I am also using this in my 55 gallon which is a 48" long tank. I think on the bigger tanks you may need to use several SCWD's to make it effective. Oh I also like the fact that I get the wave motion in the tank and have no powerheads, which means less heat
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
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Hope that helps.