Hey Tim! First of all there is no such thing as a dumb question on this board! We love to answer any question as we know it is part of the learning process!
Many years ago I used lava rock in my saltwater tank as it was free of any metals which would do harm to my tank. Have you talked to your LFS about using various types of rock?
If you are wanting to put other rock in your tank to save on cost----it may cost you dearly in the long run!
Reading as suggested in earlier posting is an excellent way to determine what rock you will put in your aquarium. Most hobbyist use Fiji, Marshalls,
Tonga branch, etc in their reef set-up.
If your tank is large you can buy
base rock for the bottom and add show type or premium grade Live rock for topping off your reef. HTH Johnny
