that was realy helpfull but my larva rock is white not black so now im not to sure but i bourght it as lava rock/volcanic rock it is realy heavy with holes through it and what look like focils in it it is rough and smooth in parts so now im not to sureyou may wish to checkout the rocks link in my sig
It will affect your ph making it more alkaline. As said perfect for marine and malawi setups but not for your average community.