Hi,
Nope - i quote, "Lava rock is terrible for saltwater aquariums. I am a reefer, and lava rock will cause hard metals to leach into the tank. The project is cool, but it will prevent you from keeping inverts and corals. It is also a very bad bacteria culturer. It is porous, but those holes quickly get clogged with ditritus and other stuff". For simple set ups all we need is activated carbon ships for media. Advanced systems you've got your bio pellets etc.
All the best!