I was just trying to give you a reference, but I really do think two rw-4 would be enough and you could turn up the speed, it has about 8 speed settings and two pumps on 1 is plenty in a 24x24.
I don't use the wave maker, but adding that to the mix there is massive flow from these small pumps.
Also, the max speed for a RW-4 is 1056gph, and I just looked at a hydor online and one that does 1056gph is rated for a 45-75 aquarium.