I'm happy with lava rocks.

TomM in NY wrote:

I want to switch from using pea gravel to a better medium in my bio filter
(made out of a plastic milk crate with cut to size furnace filter surrounding
the inside-the pea gravel was inside and my pump was in the middle of the pea
gravel).
I cannot believe how much bio balls are....seems pretty expensive for plastic
balls!!! Anyone have any cheaper suggestions?

Thanks,
tom