[billdogg]

Here's what I use for my 120g SPS dominant DT (standard 4x2x2)

2 x Maxspect Gyre 250's on the back glass on either side of my center overflow ~1/3 of the way down and angled up a little. They max out at 70% - anything more and there is a wave crest over the front of the tank.

In addition, 2 x Koralia 1500gph, on in each back corner, again ~ 1/3 down and angled up and towards the center front

That combo gives me great circulation everywhere except behind the rockwork. For back there, I use a pair of Koralia 850's, mounted on the side near the bottom and pointed slightly upwards towards the other side

I figure that when everything is running at once I get somewhere around 80x in tank turnover. That does not include my return pump.