IMO
i like to see at least 10 x's your gallonage per hour, and enough pumps to move all the water, you don;gt want any "dead spots" in your aquarium, in your case, i'd say 3 or 4 and a total combined out put of 750 gallons(can go as high as 20x in a reef with lots of rock, but at least 10x)
HTH