I would suggest placing about 1 inch of live sand on the bottom of the aquarium. Then place the live rock right on the sand. If your reef aquarium is already well established, make sure you get the sand behind and around the reef structure when you add it.
Aquarium Filters & Filter Media: Live Sand as Refugium Substrate
United Sates Patent No. 6,376,229 issued on April 23, 2002 for a new method of preserving marine bacteria. Using the patented method Nature’s Ocean® harvests and packages live sand with an optimal amount of water and air in retail packaging specifically dimensioned and configured for maintaining ammonia oxidizing bacteria in a state wherein the bacteria are capable of metabolic and physiologic activity in excess of twelve months at room temperature. When introduced into an aquarium Nature’s Ocean® Bio-Activ Live® Aragonite Reef Sand instantly begins the cycling process which provides an optimal environment for marine life.
Aquarium Live Sand for Marine Fish and Reef Tanks - Nature's Ocean
Compared with dry sand, live sand can be expensive…but if you must get your aquarium up, running and filled with livestock immediately, it can be a time-saving product.
Mixing Sand with Live Sand | 3reef Aquarium Forums
Nature’s Ocean Aquarium Sand:
• Every grain of sand in the ocean is covered with a biofilm. Nature’s Ocean® Bio-Activ Live™ Aragonite is naturally from the ocean. The bacteria on the sand are in a biofilm, therefore the bacteria are in their natural state,immediately removing toxic waste.Biological filtration, in a saltwater aquarium, is performed by bacteria that grow on the live rock and on the live sand in your aquarium. Aquarium sand is a substrate with a lot of surface area and creates a perfect home for those biologically beneficial bacteria to grow on. But that doesn’t mean that you have to have a sand bed to have a good biological filter. Plenty of aquarists are successful keeping reef tanks with absolutely no sand bed at all. These tanks are often referred to as bare bottom tanks. But plenty of life will inhabit your sand bed if given the chance.