I kinda am going the same direction as you. I started my second tank for primarily corals and clams. I have a 40 gallon long tank. I went with MH
lighting because I wanted to go mainly sps
corals. You'll want to think what kind of corals you want to go with. sps
corals demand high lighting and water movement.
You'll really want to do a sump for filtration. I'd also get some LR
rubble for the sump too. I have almost 60 lbs of LR
in my 40 and I'm thinking of stuffing in a couple of more pieces in the tank.
I've also had great luck with two of the Korlia's(2) powerheads. They provide the flow the sps
Oh, and lastly, I did a sand bed of approximately 2 inches. I don't remember the exact lbs of the sand.
I'm sure you'll get some experts to chime in here