landscape lava rock?

[Serpentman]

I am planning my sump system and had a question. My plan is to fill 1/2 of the sump with dead rock to add additional biofiltration capacity. My thought was to use crushed landscape lava found at HD. Personally, I can't see how this is much different than the stuff sold at the LFS, however, I figured I would check here first. Is this ok to use?

 

[melosu58]

I just saw a thread not too long ago that someone just ruined his tank by using Lava Rock. Go up to the search and type lava rock. It was not long ago and several people said it could not be used I think.