Hey Tyler,
We planned on going with a 24" front-to-back depth, but at the urging of others here, we pushed out to 30". We've been very happy with the tank so far. I've to say though, I'm still a little leary on drilled holes in the bottom of the tank...
We are running a full DSB for now. Initially we struggled with the new Southdown sand because it was blowing EVERYWHERE. Things finally settled down and we have a lot of flow. Our closed loop pulls from two 2" drains through the bottom of the tank and floods the inlet to a Sequence 4200SEQ12. From there we go into a gate valve for flow control and out to an OM 4-way. Two 1.5" drains come back up through the bottom of the tank and tee just above the sand level into a 90Ã"šÃ‚° and 45Ã"šÃ‚° black PVC fitting. Two additional 1.5" returns come over the top of the tank at the front in opposite corners. The ones in/under the rock structure makes for some nice flow down low without blasting everything. The returns alternate from top to bottom and left to right so we get a constant swirling action.
One other thing we did was have Paul modify a drum for us on the OM 4-way. He turned it down through the middle to allow some blow by and keep the sand out of the drum during the first few months of settling the sand. I've only had to tear down the 4-way once and it was because I forgot to turn it off when I was moving lots of rock around.
The sump return comes from a GenX 55HP that splits into two 1.5" black PVC drops over the back of the tank.