I'm using a Dolphin Diamond Amp Master that I picked up dirt cheap. I was going to use a Dart hybred, but the Dolphin was soo cheap. I couldnt pass it up. Im pretty happy with it, almost no heat transfer, and its really quiet. My last Vortec's were just as loud. I think its around 3600 gph running wide open for the closed loop, and just a simple Mag 12 for the return/chiller. There is so much flow in the tank, it looks like the water is boiling. Im just trying to figure out exactly how I want the returns on the closed loop. I just have 45's for now, but they seem to be working well. I think I might heat up the ends and flatten and spread out the end to make the water flow spread out a little more. Right now its kinda of like a hot tub jet and sprays the water in a pretty direct stream. Im just trying to fine turn the flow.
Im really happy with the tank though. No power heads, no visible wires running up to the floating canopy. All the wires are ran internally, through the two canopy supports. I have the tank all set up like I dreamed, now I just have to master the whole coral growing part. This tank is going to stay set up just as it sits for years to come. (this is my 6th tank in 3 years)
Just FYI-Im a huge fan of minimal rock. Its easier to get good water circ, and makes the tank super easy to clean. Just not as many places to place coral. you have to pick a little more carefully when space is limited.