"ManWorld42" wrote in message
...
I was looking at some at my local Home Depot. The rocks seem very
porous and probably can support quite a good bio filter. Anyone with
experience with these rocks instead of gravel?

If used as a substitute for gravel, then I wouldn't have any bottom
feeders, as the stones are usually quite sharp edged & abrasive. There
are very good at harbouring micro-organisms (especially for feeding
newborn fry), however they are equally good are harbouring less desirable
things, like rotting detritus and algaes, so ymmv. As stonework, I
usually don't recommend them as it's too easy for fish to damage their
sides on them (especially when they get caught between a lava rock and
the glass). jmo
--
www.NetMax.tk