Dave -- Lava soils (and reefs) on volcanic islands become fertile over geologic time, not just through dilution but also through succession by waves of plant and animal life. Primary plants grow in the fertile surface ash until their roots reach the toxic sulpher lava underneath, then die, rot, and over generations make soil for secondary and tertiary plants. There are even sulpher eating bacteria that act to gas out the toxic sulpher over time as Hydrogen Sulphide. If you go to Hawaii, look for the edge of a lava flow where the life has returned and work out into the barren lava field. You'll see the whole basic evolutionary process of plant and animal succession reprised in the space of a few hundred yards. But you probably can't do the same thing in a small reef tank in any reasonable amount of time. Age real volcanic natural lava like it was Aragocrete before even thinking of using it. But even then if it breaks the newly exposed inside surfaces may carry and release poison minerals.
Mouse -- In my tanks I have used both "lava rock" (the man-made kind) and tufa as base rock. I now prefer the lava rock, as it is both less dense and more porous.
Try this test -- wet a piece of each type of rock, drain them off just 'til they stop dripping, and see which dries first -- usually the tufa will dry way before the lava, as the lava has more nooks and crannies to hold water through surface tension. This means it has much more "wetted surface area" per pound than tufa, and lots of wetted surface area is what makes potential good live rock.
I have a new tank I started in March with lots of dark red "lava rock" and a few small pieces of Premium Aquatics Fiji live rock. Now, eight months later under just mixed VHOs, the lava rock looks just like the Fiji -- totally purple coraline covered, and growing Halimeda, fan worms, sponges, sea squirts, and etc.
I've never had a problem with man-made lava, the unnatural color will be hidden inside a year, and best of all it is readily available and is cheap, cheap, cheap. You should be able to drill and shape it at least as well as the tufa by using carbide bits.
Mouse -- In my tanks I have used both "lava rock" (the man-made kind) and tufa as base rock. I now prefer the lava rock, as it is both less dense and more porous.
Try this test -- wet a piece of each type of rock, drain them off just 'til they stop dripping, and see which dries first -- usually the tufa will dry way before the lava, as the lava has more nooks and crannies to hold water through surface tension. This means it has much more "wetted surface area" per pound than tufa, and lots of wetted surface area is what makes potential good live rock.
I have a new tank I started in March with lots of dark red "lava rock" and a few small pieces of Premium Aquatics Fiji live rock. Now, eight months later under just mixed VHOs, the lava rock looks just like the Fiji -- totally purple coraline covered, and growing Halimeda, fan worms, sponges, sea squirts, and etc.
I've never had a problem with man-made lava, the unnatural color will be hidden inside a year, and best of all it is readily available and is cheap, cheap, cheap. You should be able to drill and shape it at least as well as the tufa by using carbide bits.
