CB24
Sand and Rock. The Sand is where most of your live bacteria would be, the Rock would just be for them to swim around. If I did build my shark tank, I would put Sand in the bottom of it. It would be like the tank at the New Port Aquarium. You can pet the sharks there, and they have a place to hide when they feel like they don't want to be bothered. My tank of course wouldn't be a petting zoo, but it would be the same design. Large open water tank with sand on the bottom and some live rock to swim in and out of. I would put the Bamboo Shark and Cat Shark into the tank. Being it would be big I would have about 3 each for a total of six sharks. I think it would be a cool project to have, and like I said, I don't think it would cost much.
If you referring to the pool idea, than yea! You would still need sand and some rocks for the sharks to hide in if they want. It would also help with the filtration.