I was able to run a 29g tank with two 750's and had no hurricanes within the tank.
It's all a matter of placement and angles. You definitely want as much flow as you can logically get. I happen to have 2 425's in my 20g now and it's no where near enough. lol
180g Reef - 60g Rimless Reef -90G FOWLR- 125g Malawi Cichlids- 40b REEF- 34g Fresh Planted-working on- 20L FOWLR- working on
I have a mix of many different saltwater fish amongst my tanks, but I love my Tangs most of all.