Just curious why you are only going with 20 inches of height on the aquarium? With that amount of depth, more height would give you a lot more freedom to aqauscape, and give your corals more room to grow in to before they start blocking the rock structure and corals that are towards the rear part of the aquarium. Just my 2 cents coming from a guy with a 47 wide x 31 deep x 19 high aquarium.